Blow a high note: put in valve (8)
I believe the answer is:
stopcock
'valve' is the definition.
(I've seen this before)
'blow a high note put' is the wordplay.
I cannot really see how this works, but
'high' could be 'top' (associated in meaning) and 'top' is found within the answer.
'note' could be 'c' (musical note) and 'c' is located in the answer.
'blow' could be 'sock' (I have seen 'Hard blow ' mean 'sock' so perhaps 'blow' could also mean 'sock') and 'sock' is found within the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for stopcock that I've seen before include "water regulator" , "Regulator of flow" , "Water controlled by this" , "Water/gas supply valve" , "bit of plumbing" .)