Should such a stool be soft? (5)
I believe the answer is:
piano
'soft?' is the definition.
('piano' can be similar in meaning to 'soft')
'should such a stool' is the wordplay.
I cannot really understand how this works, but
'a' could be 'an' and 'an' is found within the answer.
This explanation may well be incorrect...
'be' is the link.
Can you help me to learn more?
(Other definitions for piano that I've seen before include "Direction in music (1): relatively softly" , "Musical instrument - softly, please" , "entertain with this softly" , "Stringed instrument - to be played quietly" , "Franz Liszt's instrument" .)