Hear about British drug treatment (5)
I believe the answer is:
rehab
'drug treatment' is the definition.
(I know that Rehab is a type of drug treatment)
'hear about british' is the wordplay.
'about' is an anagram indicator.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'hear' anagrammed gives 'reha'.
'reha'+'b'='REHAB'
(Other definitions for rehab that I've seen before include "brief convalescence?" , "Rehabilitation (abbrev.)" , "Course of treatment for addicts" , "remedial treatment" , "Restorative care" .)