Grounded winger with United after end of season (5)
I believe the answer is:
nandu
'grounded winger' is the definition.
(flightless bird)
'with united after end of season' is the wordplay.
'with' becomes 'and' (I've seen this before).
'united' becomes 'u'.
'after' says to put letters next to each other.
'end of season' becomes 'n' (I can't explain this - if you can you should believe this answer much more).
'and'+'u'='andu'
'andu' put after 'n' is 'NANDU'.
(Other definitions for nandu that I've seen before include "rhea" , "South American winger" .)