Relative anxious for material (7)
I believe the answer is:
nankeen
'material' is the definition.
(nankeen is a type of material)
'relative anxious' is the wordplay.
'relative' becomes 'nan' (informal term for a grandmother).
'anxious' becomes 'keen' (I've seen this before).
'nan'+'keen'='NANKEEN'
'for' is the link.
(Other definitions for nankeen that I've seen before include "Hard-wearing fabric, originally from China" , "Yellowish cotton cloth" , "Buff colour(ed cloth)" , "mustard colour" , "Chinese cotton cloth" .)