“Mother,” you enquire. “What is that material?” (6)
I believe the answer is:
damask
'that material?' is the definition.
(damask is a kind of material)
'mother you enquire' is the wordplay.
'mother you' becomes 'dam' (I can't justify this - if you can you should give a lot more credence to this answer).
'enquire' becomes 'ask' ('ask' can be a synonym of 'enquire').
'dam'+'ask'='DAMASK'
'what is' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for damask that I've seen before include "Red" , "Rich, heavy fabric with a pattern woven into it, a tablecloth say" , "heavy embossed table linen" , "Patterned material" , "Figured material" .)