I sell new cotton fabric (5)
I believe the answer is:
lisle
'cotton fabric' is the definition.
(lisle is a type of fabric)
'i sell new' is the wordplay.
'new' is an anagram indicator.
'i'+'sell'='isell'
'isell' with letters rearranged gives 'LISLE'.
(Other definitions for lisle that I've seen before include "(Fabric woven with) a fine cotton thread" , "Twisted yarn" , "Strong tightly twisted cotton thread" , "Strong cotton material" , "Strong cotton fabric" .)