Throw cats out (4)
I believe the answer is:
cast
'throw' is the definition.
(I know that cast is a type of throw)
'cats out' is the wordplay.
'cats' becomes 'casts' ('cast' can be a synonym of 'cat').
'out' means to remove the last letter.
'casts' with its last letter taken away is 'CAST'.
(Other definitions for cast that I've seen before include "Play's actors" , "Provided players" , "Throw a fishing line" , "The acting complement of a play" , "Character" .)