Possible Clues:

• Type that's rarely in bar seat
• One declining to vote
• Seat in bar maybe not his?
• Sailor-composer used to refraining
• Sailor's instructor has no right to be the one who never gets soaked
• One practising self-denial in a British town? Almost right
• Sailor drunk retsina, which I wouldn't do
• One refusing hard stuff cooked brains and ate
• One who doesn't eat in bars free
• Non-drinker