Daddy becomes priest (6)
I believe the answer is:
This clue is a double definition.
'daddy' is the first definition.
(I know this)
'priest' is the second definition.
(father is the title for a priest)
'becomes' acts as a link.
(Other definitions for father that I've seen before include "Progenitor" , "Male parent" , "relation" , "Originate; priest" , "Relative and priest" .)