Seals in small shacks (5)

I believe the answer is:

shuts

'seals' is the definition.
(I've seen this in another clue)

'small shacks' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'shacks' becomes 'huts' ('hut' can be a synonym of 'shack').
's'+'huts'='SHUTS'

'in' acts as a link.

(Another definition for shuts that I've seen is " Closes".)

I've seen this clue in The Mirror.

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