In which a composer jots down his ideas? (8)
I believe the answer is:
notebook
'in which a composer jots down his ideas?' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
This is the entire clue.
Can you help me to learn more?
(Other definitions for notebook that I've seen before include "Token boo as in pocket recorder with blank pages (8)" , "Jotter's accessory?" , "Bigger than diary, smaller than laptop" , "little computer" , "Small volume for brief records" .)