Locking device made in nickel at Charleston (5)

I believe the answer is:

latch

I'm a little stuck... Click here to teach me more about this clue!

'locking device' is the definition.
'latch' can be an answer for 'device' (latch is a kind of device). I am unsure of the 'locking' bit.

'in nickel at charleston' is the wordplay.
'in' indicates the answer is hidden within the clue.
'LATCH' can be found hidden inside 'nickel at charleston'.

'made' is the link.

Can you help me to learn more?

(Other definitions for latch that I've seen before include "Door-fastening" , "Light door lock" , "Bar to close" , "Gate fastener" , "Door-catch" .)

I've seen this clue in The Globe and Mail.

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