One sliding in card from most valued suit: hearts win (7)
I believe the answer is:
triumph
'win' is the definition.
(triumphing is a kind of winning)
'one sliding in card from most valued suit hearts' is the wordplay.
'one' becomes 'i' (Roman numeral).
'sliding in' indicates putting letters inside.
'card from most valued suit' becomes 'trump'.
'hearts' becomes 'h' (abbreviation used in card games e.g. bridge).
'i' going into 'trump' is 'triump'.
'triump'+'h'='TRIUMPH'
(Other definitions for triumph that I've seen before include "Exultant victory" , "Outstanding victory" , "hit" , "celebrate victory" , "The exultation of victory" .)