Victory banner raised to welcome Hearts player (4-4)

'player' is the definition.
(position in some sports)

'victory banner raised to welcome hearts' is the wordplay.
'victory' becomes 'win' (a win is a victory).
'banner' becomes 'flag' (I've seen this in another clue).
'raised' says the letters should be written backwards (going up in a down clue).
'to welcome' is an insertion indicator (in sense of 'inviting in').
'hearts' becomes 'h' (abbreviation used in card games e.g. bridge).
'flag' in reverse letter order is 'galf'.
'galf' going around 'h' is 'ghalf'.
'win'+'ghalf'='WING-HALF'