Say nice things to father holding milky coffee (7)
I believe the answer is:
flatter
'say nice things to' is the definition.
'father holding milky coffee' is the wordplay.
'father' becomes 'fr'.
'holding' is an insertion indicator.
'milky coffee' becomes 'latte' (I've seen this before).
'fr' placed around 'latte' is 'FLATTER'.
(Other definitions for flatter that I've seen before include "with fewer bubbles" , "Compliment dishonestly" , "Use soap" , "flannel" , "Fawn, blandish" .)