Wind instrument - blow me having score to follow (6)
I believe the answer is:
'wind instrument' is the definition.
(cornet is a kind of wind instrument)
'blow me having score to follow' is the wordplay.
I cannot really understand how this works, but
'score' could be 'net' (I've seen this before) and 'net' is found in the answer.
The remaining letters 'cor' 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 cornet that I've seen before include "Cavalry officer" , "play this?" , "Small trumpet or ice-cream holder" , "its contents cold" , "A short trumpet or ice-cream holder" .)