A unit of weighty material importance (6)

I believe the answer is:

denier

I'm a little stuck... Click here to teach me more about this clue!

'a unit' is the definition.
(I know that denier is a type of unit)

I can't explain the remainder of the clue.

(Other definitions for denier that I've seen before include "measure of yarn's quality" , "Unit of weight of nylon, etc" , "One refusing to admit" , "One unwilling to accept" , "Units of weight in silks, nylon and other yarns" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app