Bar he built that boozer would avoid? (5)
I believe the answer is:
rehab
'that boozer would avoid?' is the definition.
(an alcoholic might avoid going to rehab)
'bar he built' is the wordplay.
'built' is an anagram indicator.
'bar'+'he'='barhe'
'barhe' anagrammed gives 'REHAB'.
(Other definitions for rehab that I've seen before include "Treatment for alcohol abuse" , "Place to go, in short, to be restored to fitness" , "Alcohol clinic" , "A herb (anag.)" , "brief convalescence?" .)