Small narrow part of latch (5)

I believe the answer is:

sneck

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'latch' is the definition.
Both the definition and answer are singular nouns.
Perhaps there's a link between them I don't understand?

'small narrow part' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'narrow part' becomes 'neck' (I've seen this before).
's'+'neck'='SNECK'

'of' acts as a link.

Can you help me to learn more?

I've seen this clue in The Guardian.

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