Toss cats out (4)
I believe the answer is:
cast
'toss' is the definition.
(I've seen this before)
'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 "Throw out line for fish" , "Shed - actors" , "Discard; actors (in play)" , "Form < > company" , "Thrown" .)