Claimant's answer caught cocaine addict (7)
I believe the answer is:
accuser
'claimant's' is the definition.
(synonyms)
'answer caught cocaine addict' is the wordplay.
'answer' becomes 'a' (abbreviation eg in Q and A).
'caught' becomes 'c' (cricket abbreviation).
'cocaine' becomes 'C' (drugs abbreviation).
'addict' becomes 'user' (drug user).
'a'+'c'+'c'+'user'='ACCUSER'
(Other definitions for accuser that I've seen before include "One who blames" , "Person making a charge" , "One making allegation" , "Person blaming" , "Prosecutor" .)