Tricks won in clubs and hearts, without a king (6)
I believe the answer is:
cheats
'tricks' is the definition.
'clubs and hearts without a king' is the wordplay.
'clubs' becomes 'c' (abbreviation used in card games such as bridge).
'and' means one lot of letters go next to another.
'without' is a deletion indicator.
'a king' becomes 'r' (r is abbreviation for rex).
'hearts' with 'r' removed is 'heats'.
'c'+'heats'='CHEATS'
'won in' acts as a link.
(Other definitions for cheats that I've seen before include "Swindles, defrauds" , "Swindles in chaste manner" , "Fixes" , "Defrauds of sachet" , "Chaste sort of swindlers" .)