Sing out the bass, easing the tempo (7)
I believe the answer is:
slowing
'easing the tempo' is the definition.
The answer and definition can be both related to change as well as being present participle verbs.
Maybe there's an association between them I don't understand?
'sing out the bass' is the wordplay.
'out' indicates putting letters inside.
'the bass' becomes 'low' (I've seen this in another clue).
'sing' going around 'low' is 'SLOWING'.
Can you help me to learn more?
(Other definitions for slowing that I've seen before include "Getting less fast" , "Decelerating" , "Checking" , "Losing pace" .)