Grandmother piercing strong fabric (7)
I believe the answer is:
nankeen
'strong fabric' is the definition.
'nankeen' can be an answer for 'fabric' (nankeen is a kind of fabric). I am not sure about the 'strong' bit.
'grandmother piercing' is the wordplay.
'grandmother' becomes 'nan' (nan can informally mean a grandmother).
'piercing' becomes 'keen' (synonyms).
'nan'+'keen'='NANKEEN'
Can you help me to learn more?
(Other definitions for nankeen that I've seen before include "Buff-coloured cotton cloth" , "Chinese cotton cloth" , "hard-wearing stuff" , "trouser material" , "Yellowish stuff" .)