Bet in old currency (4)
I believe the answer is:
punt
This clue could be a double definition.
'bet' is the first definition.
(punting is a kind of betting)
'old currency' is the second definition.
'punt' can be an answer for 'currency' (I have seen 'Former currency' mean 'punt' so perhaps 'currency' could also mean 'punt'). I'm not sure about the 'old' bit.
'in' is the link.
Can you help me to learn more?
(Other definitions for punt that I've seen before include "old money abroad" , "What the Irish used" , "Boat with pole - bet" , "Bet (in old Irish money?)" , "taken by a better" .)