Believer has drug overdose first (9)
I believe the answer is:
methodist
'believer' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'drug overdose first' is the wordplay.
'drug' becomes 'meth' (meth is a kind of drug).
'overdose' becomes 'o.d.' (synonyms).
'first' becomes 'ist' (ist resembles mst).
'meth'+'od'+'ist'='METHODIST'
'has' acts as a link.
Can you help me to learn more?
(Other definitions for methodist that I've seen before include "Protestant who follows teaching of John and Charles Wesley" , "Wesleyan" , "Follower of John and Charles Wesley" , "A follower of Wesleyanism" , "member of congregation?" .)