Club anger after United's cast down (10)
I believe the answer is:
discourage
'cast down' is the definition.
(thesaurus)
'club anger after united's' is the wordplay.
I cannot quite see how this works, but
'club' could be 'disco' (night club) and 'disco' is found within the answer.
'anger' could be 'rage' (rage is a kind of anger) and 'rage' is located in the answer.
'united' could be 'u' (abbreviation as in Man U for Manchester United) and 'u' is found in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for discourage that I've seen before include "Put off" , "Deter; dishearten" , "Talk out of" , "Try to stop" , "Cause loss of enthusiasm in (someone)" .)