Tips from Tom Hanks in leading role, mainly (3,3,4,4)
I believe the answer is:
for the most part
'mainly' is the definition.
(I've seen this before)
'tips from tom hanks in leading role' is the wordplay.
I cannot quite see how this works, but
'from' could be 'o' (I've seen this in other clues) and 'o' is found within the answer.
'role' could be 'part' (eg a part or role in a film) and 'part' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for for the most part that I've seen before include "Mainly" , "Chiefly" , "in general" , "Usually" .)