Feeling love fades for Buckley’s second melody (4)

I believe the answer is:

tune

I'm a little stuck... Click here to teach me more about this clue!

'melody' is the definition.
(I know that melody can be written as tune)

I can't explain the remainder of the clue.

(Other definitions for tune that I've seen before include "Song" , "temper" , "Adjust (car engine); air" , "'He who pays the piper calls the ...'" , "Optimise the condition of" .)

I've seen this clue in the Sydney Morning Herald.

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