Deal with composer, we're told (6)
I believe the answer is:
handle
'deal with' is the definition.
(synonyms)
'composer we're told' is the wordplay.
'composer' becomes 'handel' (George Frideric Handel).
'we're told' indicates a 'sounds like' (homophone) clue.
'handel' is a homophone of 'HANDLE'.
(Other definitions for handle that I've seen before include "Part by which something is carried" , "Ability to walk on board ship" , "Treat" , "Get a grip" , "Manage or deal with - in manual way?" .)