Answer by friend upset cleric, causing fuss (7)
I believe the answer is:
palaver
'fuss' is the definition.
(I've seen this before)
'answer by friend upset cleric' is the wordplay.
'answer' becomes 'a' (abbreviation eg in Q and A).
'by' means one lot of letters go next to another.
'friend' becomes 'pal' (pal is a kind of friend).
'upset' shows that the letters should be reversed in order.
'cleric' becomes 'Rev' (abbreviation for Reverend).
'rev' reversed gives 'ver'.
'a' after 'pal' is 'pala'.
'pala'+'ver'='PALAVER'
'causing' acts as a link.
(Other definitions for palaver that I've seen before include "Confused talk and activity" , "Prolonged fuss" , "Time-consuming business" , "Hubbub; lengthy fuss" , "Rabbit" .)