Diamond-shaped pattern used in knitwear (6)
I believe the answer is:
argyle
(Other definitions for argyle that I've seen before include "Knitted or woven with diamond-shaped pattern" , "Old Scottish county; part name of a W Country football team" , "Design of diamond shapes, based on a Scottish clan tartan" , "Coloured diamond pattern on knitted garments" , "See 10" .)