So, is 1 Peter 3:15 the "Great Commission for Apologetics" or an exhortation to be ready to give your testimony? The word translated "answer" is apologia, the word from which we get the English word "apologetics." It may mean a verbal defense or a reasoned statement. The word itself could include either. What may we glean from the context?
The immediate context is the sentence of 1 Peter 3:14-16: But and if ye suffer for righteousness' sake, happy are ye: and be not afraid of their terror, neither be troubled; But sanctify the Lord God in your hearts: and be ready always to give an answer to every man that asketh you a reason of the hope that is in you with meekness and fear: Having a good conscience; that, whereas they speak evil of you, as of evildoers, they may be ashamed that falsely accuse your good conversation in Christ.
The broader context contains instructions for the behavior of God's people, beginning in 2:11. This includes submission of Christians to law & government, of servants to masters, or wives to husbands. Giving an answer is part of that behavior, a dual submission to God and man. A submission to God in having and giving an answer, and submission to man in giving an answer to those who ask. Christians should live in fear of God and not what man might do. Disciples may suffer for righteousness sake, but do not recoil in fear.
Rather than fear what man might do, let us sanctify/separate/set apart the Lord in our hearts. Isaiah writes, "Sanctify the LORD of hosts himself; and let him be your fear, and let him be your dread (Isaiah 8:13)." The Lord God is the one we are to regard as holy; let us set that aside in our hearts and act accordingly. This prepares us to be "be ready". We are to be ready to "give an answer". This answer is apologia, a reasoned statement of why there is a hope within us. We can and should search the scriptures, rightly divide the word of truth and earnestly contend for the faith once delivered to the saints. But let us not forget the simplicity of the untutored new creature showing "how great things God hath done unto thee. Luke 8:39)."
The witness here is not one of evangelism, but a witness or answer to those who ask or inquire honestly (or authoritatively) concerning our hope. Some Bible students believe that this should be connected to the submission to authorities as taught in chapter 2. If so, the readiness advised may be considered more prayerful and spiritual rather than academic, for Jesus told His apostles when they were brought to the synagogues, and before magistrates and authoritiess, they were to take "no thought how or what thing ye shall answer, or what ye shall say -- For the Holy Ghost shall teach you in the same hour what ye ought to say (Luke 12:11-12)." This doesn't sound like a prepared speech or programmed answer.
John Gill writes that the answer should not be delivered in a light, trifling, and negligent manner, and no part of truth be dropped or concealed in order to please men. Further he encourages it be answered with all due respect to all men, especially the civil magistrates, who may ask the reason, with a reverence suitable to the subject.
We should give answer with meekness and fear (fear God more and fear men less, Luke 12:4-5). Our answers to men are with respect towards man, and proper fear or reverence towards God. If we fear God more than we fear man, we will not be afraid to "give an answer". Some avoid making their Christianity audible or visible, shy away from conflict, and either do not or seldom do give any answers to any men. Certainly we need to know to be swift to hear and slow to speak, but that advice rises from the appropriate application of wisdom, not from being mute concerning our faith. The intent includes deflecting false accusations off oneself, but particularly because it is reflection on the Christian profession. Do it all in good conscience, with good intent and good conversation that contradicts the false accusations and embarasses the false accusers. The Christian answers, keeping a good conscience, which others cannot see and displaying good behaviour, which which others can see. We do what is right no matter what.
The answering Christian resigns to God's will and way, "If we suffer, we suffer." We live in a world of perpetual suffering, and how much better it is to suffer for doing good rather than suffer for doing wrong! In Peter's instruction we hear echoes of the words of the "3 Hebrew children": God is able to deliver us, we believe He will deliver us, but if not, we will serve the Lord regardless.