Chap unfit to work on a tough paper (7)
I believe the answer is:
manilla
'a tough paper' is the definition.
'manilla' can be an answer for 'paper' (manilla is a kind of paper). I am unsure of the 'a tough' bit.
'chap unfit to work on' is the wordplay.
'chap' becomes 'man' (chap can mean a man).
'unfit' becomes 'ill' (associated in meaning).
'to work on' becomes 'a' (I can't justify this - if you can you should believe this answer much more).
'man'+'ill'+'a'='MANILLA'
Can you help me to learn more?
(Other definitions for manilla that I've seen before include "cigar" , "Hemp fibre" , "West African bracelet; sounds like capital of thirty across" , "type of brown paper" , "Bracelet made of metal" .)