One who nibbles the leaves of books, etc? (7)
I believe the answer is:
browser
'one who nibbles the leaves of books etc?' is the definition.
The definition suggests a singular noun which matches the answer.
This is the entire clue.
Can you help me to learn more?
(Other definitions for browser that I've seen before include "Giraffe, say" , "deer" , "program to trawl the net" , "surveyor" , "Program for perusing the Web" .)