Crossword Genius

They say thin is right (4)

Ross

I believe the answer is:

lien

'is right' is the definition.
(legal right)

'they say thin' is the wordplay.
'they say' shows a homophone (sound like).
'thin' becomes 'lean' (associated in meaning).
'lean' sounds like 'LIEN'.

(Other definitions for lien that I've seen before include "Security for a debt" , "Right to a lawyer" , "The right to take property if an obligation is not met" , "Right to retain property until a debt is paid" , "Legal claim on Nile" .)

I've seen this clue in The Guardian.
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