Bottom's part given full expression too much? (4,3,3)
I believe the answer is:
over the top
'too much?' is the definition.
'bottom's part given full expression' is the wordplay.
I cannot really understand how this works, but
'part' could be 'top' (top is a kind of part) and 'top' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for over the top that I've seen before include "Away from the trenches" , "Where the circus flag might be" , "To an excessive degree" , "a bit much" , "To an exaggerated degree" .)