Material apt to stain badly? (5)

I believe the answer is:

satin

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

'material' is the definition.
(satin is a kind of material)

'apt to stain badly?' is the wordplay.
'stain' can be anagrammed to 'SATIN'.
Though, I'm unsure how this is indicated.

Can you help me to learn more?

(Other definitions for satin that I've seen before include "Rich cloth" , "Smooth glossy fabric" , "Smooth and silky" , "Stain on shiny fabric" , "covered with?" .)

I've seen this clue in the Evening Standard.

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