Bet it's a boat! (wordplay terrible at first) (4)
I believe the answer is:
punt
'bet' is the definition.
(I know that punt is a more specific form of the action bet)
'wordplay terrible at first' is the wordplay.
'wordplay' becomes 'pun' (synonyms).
'at first' says to take the initial letters.
The first letter of 'terrible' is 't'.
'pun'+'t'='PUNT'
'it's a boat' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for punt that I've seen before include "Stake" , "taken by a better" , "old money abroad" , "Flat-bottomed boat propelled by pole" , "gambling" .)