Material found in slum settlement (6)
I believe the answer is:
muslin
'material' is the definition.
(I know that muslin is a type of material)
'in slum settlement' is the wordplay.
'settlement' is an anagram indicator.
'in'+'slum'='inslum'
'inslum' is an anagram of 'MUSLIN'.
'found' acts as a link.
(Other definitions for muslin that I've seen before include "Lightweight cotton fabric" , "Light cotton cloth" , "dress material" , "Fine soft plain-woven cotton fabric of gauzy appearance" , "Cotton for veil or strainer" .)