That chap in pub rejected treatment for alcoholism? (5)
I believe the answer is:
rehab
'treatment for alcoholism?' is the definition.
(I've seen this before)
'that chap in pub rejected' is the wordplay.
'that chap' becomes 'he'.
'in' is an insertion indicator.
'pub' becomes 'bar' (both are drinking establishments).
'rejected' shows that the letters should be reversed in order.
'he' placed within 'bar' is 'baher'.
'baher' backwards is 'REHAB'.
(Other definitions for rehab that I've seen before include "remedial treatment" , "Alcohol clinic" , "convalescent home?" , "Treatment for alcohol abuse" , "Health-restoring process" .)