Most unexcited about song (4)
I believe the answer is:
tune
'song' is the definition.
(I know that tune is a type of song)
'most unexcited about' is the wordplay.
'about' indicates the answer is hidden within the clue (the clue goes around or about the answer).
'TUNE' is hidden in the letters of 'most unexcited'.
(Other definitions for tune that I've seen before include "Adjust a radio receiver to a frequency" , "strain" , "Optimise the condition of" , "Song" , "temper" .)