Ruins hiding English creatures (5)

I believe the answer is:

mares

'creatures' is the definition.

'ruins hiding english' is the wordplay.
'ruins' becomes 'mars' (I've seen this before).
'hiding' means one lot of letters goes inside another.
'english' becomes 'e' (abbreviation).
'mars' enclosing 'e' is 'MARES'.

(Another definition for mares that I've seen is " Female horses".)

I've seen this clue in The Mirror.

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