Most unexcited about melody (4)
I believe the answer is:
tune
'melody' is the definition.
(synonyms)
'most unexcited about' is the wordplay.
'about' says the answer is hidden in the clue (the clue goes around or about the answer).
'TUNE' can be found hidden inside 'most unexcited'.
(Other definitions for tune that I've seen before include "strain" , "Adjust a radio receiver to a frequency" , "Melody; adjust (engine)" , "Improve quality" , "temper" .)