Discard a team supporting actors (4,5)
I believe the answer is:
cast aside
'discard' is the definition.
('cast aside' can be a synonym of 'discard')
'a team supporting actors' is the wordplay.
'team' becomes 'side' (I've seen this before).
'supporting' means one lot of letters go next to another (in a down clue, some letters go below others).
'actors' becomes 'cast' (I've seen this before).
'a'+'side'='aside'
'aside' after 'cast' is 'CAST ASIDE'.
(Other definitions for cast aside that I've seen before include "Get rid of" , "Ditch" , "dropped" .)