Hungarian composer of memorable harmonies (5)
I believe the answer is:
lehar
'hungarian composer' is the definition.
(I've seen this before)
'of memorable harmonies' is the wordplay.
'of' says the answer is hidden in the clue.
'LEHAR' is hidden within 'memorable harmonies'.
(Other definitions for lehar that I've seen before include "Operettist" , "Franz . . . . . composed 'The Merry Widow'" , "Operetta composer" , "Hungarian who composed" , "Hungarian composer of operettas" .)