Investigations among piles of paper the writer's collected (9)
I believe the answer is:
inquiries
'investigations' is the definition.
(inquiry is a kind of investigation)
'among piles of paper the writer's collected' is the wordplay.
'among' becomes 'in' (I've seen this in other clues).
'piles of paper' becomes 'quires' (I can't explain this - if you can you should give a lot more credence to this answer).
'the writer' becomes 'i' (the person who is writing these clues).
'collected' is an insertion indicator.
'quires' placed around 'i' is 'quiries'.
'in'+'quiries'='INQUIRIES'
Can you help me to learn more?
(Another definition for inquiries that I've seen is " Examinations".)