Boy’s water in Delhi drums (7)
I believe the answer is:
timpani
'drums' is the definition.
(I've seen this before)
'boy's water in delhi' is the wordplay.
I cannot really see how this works, but
'boy' could be 'tim' (short for Timothy) and 'tim' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for timpani that I've seen before include "> kitchen equipment?" , "PM, I ain't (anag.)" , "Percussion section" , "set of instruments" , "Mini tap on a large drum" .)