Up with the lark? He's famous for it! (7,8)
I believe the answer is:
vaughan williams
'up with the lark? he's famous for it' is the definition.
The definition suggests a singular noun which matches the answer.
'he's famous for it' is the wordplay.
I cannot really understand how this works, but
'he's' could be 'williams' and 'williams' is found in the answer.
The remaining letters 'vaughan' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for vaughan williams that I've seen before include "English composer" , "scorer" .)