Old piece of fluff among fine tufts of wool (9)
I believe the answer is:
flintlock
'old piece' is the definition.
'flintlock' can be an answer for 'piece' (flintlock is a kind of piece). I am not sure about the 'old' bit.
'fluff among fine tufts of wool' is the wordplay.
'fluff' becomes 'lint' (I've seen this in another clue).
'among' means one lot of letters goes inside another.
'fine' becomes 'f' (abbreviation).
'tufts of wool' becomes 'lock' (I can't explain this - if you can you should give a lot more credence to this answer).
'f'+'lock'='flock'
'lint' inserted inside 'flock' is 'FLINTLOCK'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for flintlock that I've seen before include "Old musket" , "Type of firearm" , "gun" , "Piece of old" , "Weapon" .)