Boaters in Sanremo at sea (7)
I believe the answer is:
oarsmen
'boaters' is the definition.
(oarsman is a kind of boater)
'sanremo at sea' is the wordplay.
'at sea' is an anagram indicator.
'sanremo' anagrammed gives 'OARSMEN'.
'in' acts as a link.
(Other definitions for oarsmen that I've seen before include "They row the boat" , "Crew - moaners (anag)" , "A sermon about rowers" , "Male rowers" , "Male propellers of boats" .)