Regular cask has fabric, writing instruments (7)
I believe the answer is:
crayons
'instruments' is the definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Perhaps you can see an association between them that I don't see?
'regular cask has fabric' is the wordplay.
'regular' means one should take alternating letters.
'has' is an insertion indicator.
'fabric' becomes 'rayon' (rayon is a kind of fabric).
The alternate letters of 'cask' are 'cs'.
'cs' enclosing 'rayon' is 'CRAYONS'.
'writing' is the link.
Can you help me to learn more?
(Other definitions for crayons that I've seen before include "Wax pencils" , "Coloured writing sticks" , "colours" , "Coloured sticks for drawing" .)