Not being silks, they may be saints (6)
I believe the answer is:
satins
'not being silks they' is the definition.
The definition suggests an adverb but the answer is not.
'may be saints' is the wordplay.
'may' indicates anagramming the letters (I've seen 'might' mean this (I've seen this in other clues)).
'saints' anagrammed gives 'SATINS'.
Can you help me to learn more?
(Other definitions for satins that I've seen before include "Smooth shiny cloths" , "Stains on shiny cloths" , "Gives smooth surface" , "Stains on rich cloths" , "Stains on shiny fabrics" .)