Gamble with joker and heart alternately (5)
I believe the answer is:
wager
'gamble' is the definition.
(I know that wager is a type of gamble)
'joker and heart alternately' is the wordplay.
'joker' becomes 'wag' (I've seen this in another clue).
'and' means one lot of letters go next to another.
'alternately' indicates alternate letters.
The alternate letters of 'heart' are 'er'.
'wag'+'er'='WAGER'
'with' is the link.
(Other definitions for wager that I've seen before include "better to put this on?" , "Bet, gamble" , "Risk; stake" , "act for "The Gamblers"?" , "Put on a bit" .)