Presumably not the sort of textile that is whiter than white! (10)
I believe the answer is:
unbleached
'presumably not the sort of textile that is whiter than white' is the definition.
I can't judge whether this defines the answer.
'not the sort of textile that is whiter than white' is the wordplay.
I cannot quite understand how this works, but
'not' could be 'un' (prefix meaning 'not') and 'un' is found in the answer.
'white' could be 'bleach' (bleaching is a kind of whiting) and 'bleach' is found within the answer.
The remaining letters 'ed' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?