Chants may upset sailor (9)
I believe the answer is:
yachtsman
'sailor' is the definition.
(I know that sailor can be written as yachtsman)
'chants may upset' is the wordplay.
'upset' indicates an anagram.
'chants'+'may'='chantsmay'
'chantsmay' with letters rearranged gives 'YACHTSMAN'.
(Other definitions for yachtsman that I've seen before include "Male sailor" , "sportsperson involved with rigging?" , "I may go round the world" , "Description of Chichester" , "Pleasure sailor" .)