Quiet piece of computer equipment (5)
I believe the answer is:
'computer equipment' is the definition.
(I've seen this before)
'quiet piece of' is the wordplay.
I cannot really understand how this works, but
'of' could be 'o' and 'o' is present in the answer.
The remaining letters 'muse' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for mouse that I've seen before include "computer equipment" , "Small rodent - computer device" , "computer operator" , "Domestic rodent" , "PC device" .)