Terrible stain on cloth (5)
I believe the answer is:
satin
'cloth' is the definition.
(I know that satin is a type of cloth)
'terrible stain' is the wordplay.
'terrible' indicates an anagram.
'stain' anagrammed gives 'SATIN'.
'on' is the link.
(Other definitions for satin that I've seen before include "Stain on silky cloth" , "Stain found in cloth" , "Saint (anag.)" , "Silky material" , "Silk fabric" .)