Bet on a boat (4)
I believe the answer is:
punt
This clue is a double definition.
'bet on' is the first definition.
(synonyms)
'a boat' is the second definition.
(type of boat)
(Other definitions for punt that I've seen before include "Boat with pole - bet" , "Pre-euro unit of Irish currency" , "old money abroad" , "taken by a better" , "What the Irish used" .)