Stone, a hinged barrier (5)

I believe the answer is:

agate

'stone' is the definition.
(I've seen this before)

'a hinged barrier' is the wordplay.
'hinged barrier' becomes 'gate' (I've seen this before).
'a'+'gate'='AGATE'

(Other definitions for agate that I've seen before include "Striped stone" , "Quartz gem" , "Banded ornamental stone" , "Variegated chalcedony" , "Hard stone with concentric bands of colour" .)

I've seen this clue in The Telegraph.

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