Little Elizabeth's gamble (3)
I believe the answer is:
bet
'gamble' is the definition.
(bet is a kind of gamble)
'little elizabeth's' is the wordplay.
'little' means to remove the last letter (the word is not quite complete).
'elizabeth' becomes 'beth'.
'beth' with its final letter taken off is 'BET'.
(Other definitions for bet that I've seen before include "Wager, gamble" , "Speculation" , "Wager, or the sum waged" , "Wager, back" , "Wager, speculate" .)