Contracting two quintets to perform vocals (7)
I believe the answer is:
tensing
'contracting' is the definition.
The definition and answer can be both related to bodily activities as well as being present participle verbs.
Maybe they are linked in a way I don't understand?
'two quintets to perform vocals' is the wordplay.
I cannot quite see how this works, but
'perform' could be 'sing' (to perform a song) and 'sing' is found in the answer.
The remaining letters 'ten' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for tensing that I've seen before include "becoming screwed up" , "Getting taut" .)