Cartoon character father has to watch (6)
I believe the answer is:
popeye
'cartoon character' is the definition.
(comic strip character)
'father has to watch' is the wordplay.
'father' becomes 'pop ' (pop is a kind of father).
'has' is a charade indicator (letters next to each other).
'to watch' becomes 'eye' (eye can mean to watch or look at).
'pop'+'eye'='POPEYE'
(Other definitions for popeye that I've seen before include "Old cartoon sailor" , "The Sailor Man" , "Bluto's rival" , "Spinach-eating cartoon character" , "Cartoon sailor (showing amazement?)" .)