Titus 1:7  For a bishop must be blameless, as the steward of God; not selfwilled, not soon angry, not given to wine…

We interpret “not given to wine” to mean not allowing wine to influence one’s thinking, words, or actions, in any way or to any extent.  The Bible does not disallow wine.  In fact, Paul suggested to Timothy that he drink a little wine instead of water for a stomach ailment (1 Tim 5:23).  However, while the Bible does not disallow wine (or alcohol), it firmly warns against any kind of drunkenness.  Drunkenness, in and of itself, is most definitely a sin. Drunkenness alters and controls one’s mind and diminishes one’s self-control and thereby induces sins in thoughts, words, and actions.

The admonition in Titus 1:7 is that  bishops are to be above reproach. Bishops are in a leadership role in the church, so they are to be an example of living life according to God’s will and ways.  All Christians should follow the admonition not to be given to wine.  Therefore, in the selection of any church leader this is a requirement.  And, the only way to be 100% certain that one will not be “given to wine,” or any mind altering drink or drug, is to abstain from the intake of any such drink or drug.

Hope this helps in your discernment of 1 Titus 17.  For more about the drinking of wine and alcohol, you might want to read:  Is it a sin to drink alcohol?