State a mine may be in (5)

I believe the answer is:

maine

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

'state' is the definition.
(US state)

'a mine may be in' is the wordplay.
'a mine' can be anagrammed to 'MAINE'.
However, I'm unsure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for maine that I've seen before include "N. US Atlantic state" , "The USA's Pine Tree State" , "somewhere in America" , "North-easterly US state" , "American state, capital Augusta" .)

I've seen this clue in the Evening Standard.

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