Plaid (6)
I believe the answer is:
tartan
'plaid' is the definition.
(I know that plaid can be written as tartan)
This is all the clue.
(Other definitions for tartan that I've seen before include "Scots cloth pattern" , "Highland check pattern" , "Scots plaid" , "Cloth with a crisscross design" , "Distinctive pattern of a Scottish clan" .)