He composed a bit of the whole harmony (5)
I believe the answer is:
lehar
'he composed a bit' is the definition.
The definition suggests a singular noun which matches the answer.
'of the whole harmony' is the wordplay.
'of' says the answer is hidden in the clue.
'LEHAR' is hidden within 'whole harmony'.
Can you help me to learn more?
(Other definitions for lehar that I've seen before include "He scored" , "Musician" , "Viennese composer" , "Operetta composer" , "Hungarian who composed" .)