Composer of some unforgettable harmonies (5)
I believe the answer is:
lehar
'composer' is the definition.
(Austro-Hungarian composer Franz Lehar)
'some unforgettable harmonies' is the wordplay.
'some' says the answer is hidden in the clue (some parts of the word are used).
'LEHAR' can be found hidden inside 'unforgettable harmonies'.
'of' acts as a link.
(Other definitions for lehar that I've seen before include "He scored" , "Hungarian composer of operettas" , "Franz . . . . . composed 'The Merry Widow'" , "Operettist" , "Austrian of note" .)