Fridge Machinery Supplies (5)

I believe the answer is:

chine

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

'fridge' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

'machinery supplies' is the wordplay.
'supplies' indicates a hidden word (I've seen 'supplying' mean this).
'CHINE' is hidden within 'machinery'.

Can you help me to learn more?

(Other definitions for chine that I've seen before include "Ravine" , "Backbone of animal" .)

I've seen this clue in the Sydney Morning Herald.

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