Doctor chats with many a sailor (9)
I believe the answer is:
yachtsman
'a sailor' is the definition.
(yachtsman is a kind of sailor)
'doctor chats with many' is the wordplay.
'doctor' indicates anagramming the letters.
'with' means one lot of letters go next to another.
'chats' put after 'many' is 'manychats'.
'manychats' is an anagram of 'YACHTSMAN'.
(Other definitions for yachtsman that I've seen before include "Male sailor" , "Leisure sailor" , "sportsperson involved with rigging?" , "Description of Chichester" , "Member of sailing crew" .)