What American held in hands for composer (5)
I believe the answer is:
lehar
'for composer' is the definition.
(Austro-Hungarian composer Franz Lehar)
'what american held in hands' is the wordplay.
'what' becomes 'eh' (sound used to ask 'what?' or 'pardon?').
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'held in' is an insertion indicator.
'hands' becomes 'LR' (abbreviations for left and right).
'eh'+'a'='eha'
'eha' put within 'lr' is 'LEHAR'.
(Other definitions for lehar that I've seen before include "Hungarian composer of operettas" , "Franz . . . . . composed 'The Merry Widow'" , "Operettist" , "Hungarian who composed" , "Franz -----, composer of The Merry Widow" .)