Composer's somewhat cross, initially (7)
I believe the answer is:
rossini
'composer's' is the definition.
(I've seen this before)
'somewhat cross initially' is the wordplay.
'somewhat' says the answer is hidden in the clue.
'ROSSINI' can be found hidden inside 'cross initially'.
(Other definitions for rossini that I've seen before include "He composed operas" , "opera producer" , "Gioacchino ---, It. composer" , "whose barber was in Seville" , "Composer of 'The Barber of Seville' and 'William Tell'" .)