I leave fast before a complaint (7)

I believe the answer is:

lentigo

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'a complaint' is the definition.
Both the answer and definition are singular nouns.
Perhaps you can see a link between them that I don't see?

'i leave fast before' is the wordplay.
'leave' becomes 'go'.
'fast' becomes 'lent' (Lent is a period of fasting in Christianity).
'before' says to put letters next to each other.
'i'+'go'='igo'
'igo' after 'lent' is 'LENTIGO'.

Can you help me to learn more?

(Other definitions for lentigo that I've seen before include "skin discoloration" , "Spots" , "Technical name for a freckle" , "Skin condition" , "Skin disease" .)

I've seen this clue in The Hindu.

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