Groan when turning church keys? (5)

I believe the answer is:

organ

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

'church keys?' is the definition.
(I've seen this in another clue)

'groan when turning' is the wordplay.
'groan' anagrams to 'ORGAN'.
Though, I am not clear how this is indicated.

Can you help me to learn more?

(Other definitions for organ that I've seen before include "Ear, perhaps" , "Possibly stomach" , "ear maybe" , "Newspaper; instrument" , "Soft part of the body which has a specific function" .)

I've seen this clue in The Sun.

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