Expression perhaps popular with golfers, initially (6)
I believe the answer is:
saying
'expression' is the definition.
(synonyms)
'perhaps popular with golfers initially' is the wordplay.
'perhaps' becomes 'say' (both can mean 'for example').
'popular' becomes 'in' ('in' can mean trendy).
'with' is a charade indicator (letters next to each other).
'initially' suggests taking the first letters.
The first letter of 'golfers' is 'g'.
'say'+'in'+'g'='SAYING'
(Other definitions for saying that I've seen before include "Uttering" , "Gnome" , "Well-known phrase or proverb - just speaking" , "Delivering" , "Articulating" .)