Open boat in spill (7)
I believe the answer is:
lighter
This could be a double definition.
'open boat' is the first definition.
'lighter' can be an answer for 'boat' (lighter is a kind of boat). I am unsure of the 'open' bit.
'spill' is the second definition.
(thesaurus)
'in' is the link.
Can you help me to learn more?
(Other definitions for lighter that I've seen before include "Barge - alternative to match" , "Flat-bottomed barge - not so heavy" , "Boat for heavy loads and fire igniter" , "Device for igniting cigarette" , "Fire-raiser" .)