Ruddy peasant once in group (7)

I believe the answer is:

scarlet

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'ruddy' is the definition.
(I know that ruddy can be written as scarlet)

'peasant once in group' is the wordplay.
'peasant once' becomes 'carl' (I can't explain this - if you can you should believe this answer much more).
'in' indicates putting letters inside.
'group' becomes 'set' (both can mean a collection).
'carl' put inside 'set' is 'SCARLET'.

Can you help me to learn more?

(Other definitions for scarlet that I've seen before include "immoral" , "Cherry-red" , "Bright red of clarets" , "Vivid red" , "Murderer" .)

I've seen this clue in The Times.

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