Churchgoer in French capital dealt heroin (11)
I believe the answer is:
parishioner
'churchgoer' is the definition.
(parishioner is a kind of churchgoer)
'french capital dealt heroin' is the wordplay.
'french capital' becomes 'paris' ('Paris' can be a synonym of 'french capital').
'dealt' indicates an anagram.
'heroin' anagrammed gives 'hioner'.
'paris'+'hioner'='PARISHIONER'
'in' is the link.
(Other definitions for parishioner that I've seen before include "I hire parson (anag)" , "member of church community?" , "churchgoer" , "One in a local church area" .)