Bet it's joke time (4)
I believe the answer is:
punt
'bet' is the definition.
(I know that punt is a more specific form of the action bet)
'joke time' is the wordplay.
'joke' becomes 'pun' (pun is a type of joke).
'time' becomes 't' (abbreviation).
'pun'+'t'='PUNT'
'it's' acts as a link.
(Other definitions for punt that I've seen before include "Boat; Irish ex-currency" , "What the Irish used" , "Former currency of Ireland" , "Flat-bottomed boat propelled by pole" , "Bet (in old Irish money?)" .)