One knows the sound of it being blown (4)
I believe the answer is:
nose
'it being blown' is the definition.
The definition suggests a singular noun which matches the answer.
'one knows the sound' is the wordplay.
'the sound' indicates a 'sounds like' (homophone) clue.
'knows' sounds like 'NOSE'.
'of' is the link.
Can you help me to learn more?
(Other definitions for nose that I've seen before include "Hooter" , "Bouquet of wine; beak" , "Asian wind instrument -- use Teflon (anag)" , "blow it!" , "Facial organ" .)