Discolouration in satin (5)

I believe the answer is:

stain

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

'discolouration' is the definition.
(synonyms)

'satin' is the wordplay.
'satin' anagrams to 'STAIN'.
Though, I am not sure how the anagram is indicated.

'in' is the link.

Can you help me to learn more?

(Other definitions for stain that I've seen before include "Discolour - blemish" , "Dirty mark; dye" , "Spot - shame" , "Smear" , "Colour, dye" .)

I've seen this clue in the Evening Standard.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.