Father and friend of the Pope (5)
I believe the answer is:
papal
'of the pope' is the definition.
(I've seen this before)
'father and friend' is the wordplay.
'father' becomes 'pa' (pa can mean dad or father).
'and' means one lot of letters go next to another.
'friend' becomes 'pal' (pal can mean a friend).
'pa'+'pal'='PAPAL'
(Other definitions for papal that I've seen before include "Like some bulls" , "Relating to the Pontiff" , "Of the RC leader" , "of Catholic high-up" , "Of the highest Vatican authority" .)