The state a mine may be in (5)
I believe the answer is:
maine
'the state' is the definition.
(US state)
'a mine may be in' is the wordplay.
'a mine' can be anagrammed to 'MAINE'.
But, I am not sure how the anagram is indicated.
Can you help me to learn more?
(Other definitions for maine that I've seen before include "New England state" , "NE US state" , "North-east American state" , "US state, capital Augusta (5)" , "N. US Atlantic state" .)