Hilltop right in front of the boat (4)
I believe the answer is:
brow
'hilltop' is the definition.
(synonyms)
'right in front of the boat' is the wordplay.
'right' becomes 'r' (common abbreviation).
'in' indicates putting letters inside.
'front of the boat' becomes 'bow' (bow can mean the front of a boat).
'r' inserted within 'bow' is 'BROW'.
(Other definitions for brow that I've seen before include "Summit of a hill/pass" , "Hill part -- head part" , "Peak of a hill" , "Surprised one can raise this" , "Forehead, sometimes knitted" .)