Order replacement silk for pillar (7)
I believe the answer is:
obelisk
'pillar' is the definition.
(I've seen this before)
'order replacement silk' is the wordplay.
'order' becomes 'obe'.
'replacement' is an anagram indicator.
'silk' with letters rearranged gives 'lisk'.
'obe'+'lisk'='OBELISK'
'for' acts as a link.
(Other definitions for obelisk that I've seen before include "Monument with four sides and tapering top" , "Four-sided tapering pillar" , "Tapering monumental pillar" , "Cleopatra's Needle, for instance" , "Needle-like column" .)