Only a lake (4)

I believe the answer is:

mere

This clue is a double definition.

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

'a lake' is the second definition.
(I know that mere is a type of pond)

(Other definitions for mere that I've seen before include "Pond - pure and simple" , "Lake in Cumbria" , "Paltry" , "Small area of standing water" , "Lake (and nothing else?)" .)

I've seen this clue in The Mirror, The Times, The Sun and The Irish Independent.

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