Notes kept in a pocketbook perhaps (5,5)
I believe the answer is:
paper money
'pocketbook perhaps' is the definition.
I can't judge whether this defines the answer.
'notes kept in a' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'per' (eg 'one a day' means 'one per day') and 'per' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for paper money that I've seen before include "Used as legal tender in place of gold and silver" , "Banknotes" .)