Sounds on instrument after you and I hit the bottle (3,4,7)
I believe the answer is:
wet ones whistle
'hit the bottle' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'sounds on instrument after you and i' is the wordplay.
I cannot quite understand how this works, but
'sounds' could be 'tones' (tone is a kind of sound) and 'tones' is found in the answer.
'instrument' could be 'whistle' (whistle is a kind of instrument) and 'whistle' is located in the answer.
'you and i' could be 'we' (we means you and I) and 'we' is found in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for wet ones whistle that I've seen is " Have a drink".)