Egyptian believer collared when speaking (4)
I believe the answer is:
copt
'egyptian believer' is the definition.
(member of the Coptic Church in Egypt)
'collared when speaking' is the wordplay.
'collared' becomes 'copped' ('cop' can be a synonym of 'collar').
'when speaking' indicates a 'sounds like' (homophone) clue.
'copped' is a homophone of 'COPT'.
(Other definitions for copt that I've seen before include "Member of ancient Egyptian church" , "Christian in mainly Moslem country" , "Early Christian" , "Egyptian Christian Church member" .)