Block demand for fine fabric (6)
I believe the answer is:
damask
'fine fabric' is the definition.
'block demand' is the wordplay.
'block' becomes 'dam' (damming is a kind of blocking).
'demand' becomes 'ask' ('ask' can be a synonym of 'demand').
'dam'+'ask'='DAMASK'
'for' is the link.
(Other definitions for damask that I've seen before include "reversible material" , "Cloth, originally Syrian" , "Heavy patterned fabric" , "heavy embossed table linen" , "Red" .)