Deal with composer in conversation (6)
I believe the answer is:
handle
'deal with' is the definition.
(synonyms)
'composer in conversation' is the wordplay.
'composer' becomes 'Handel' (George Frideric Handel).
'in conversation' indicates a 'sounds like' (homophone) clue.
'handel' sounds like 'HANDLE'.
(Other definitions for handle that I've seen before include "Part to be grasped" , "Trade in" , "Manage or deal with - in manual way?" , "Infectious disease" , "Feel or manipulate" .)