Crease knight's cloth (5)
I believe the answer is:
linen
'cloth' is the definition.
(linen is a kind of cloth)
'crease knight's' is the wordplay.
'crease' becomes 'line' ('line' can be a synonym of 'crease'**).
'knight' becomes 'n' (chess).
'line'+'n'='LINEN'
(Other definitions for linen that I've seen before include "Flax product" , "Flaxen cloth" , "Sheets, cloths, napkins etc" , "bedsheets?" , "Fabric, originally just spun flax" .)