Excessively shortened screwdriver, perhaps (3)
I believe the answer is:
too
'excessively' is the definition.
('too' can be a synonym of 'excessively')
'shortened screwdriver perhaps' is the wordplay.
'shortened' means to remove the last letter.
'screwdriver perhaps' becomes 'tool' (screwdriver is a kind of tool).
'tool' with its final letter taken off is 'TOO'.
(Other definitions for too that I've seen before include "Excessively" , "On top - also" , "Also; overly" , "Additionally" , "Likewise" .)