Miner worried about a stay (6)
I believe the answer is:
remain
'stay' is the definition.
(I know that stay can be written as remain)
'miner worried about a' is the wordplay.
'worried' indicates an anagram.
'about' is an insertion indicator.
'miner' anagrammed gives 'remin'.
'remin' enclosing 'a' is 'REMAIN'.
(Other definitions for remain that I've seen before include "Continue in position" , "Stay, don't go" , "Airmen (anag.)" , "Marine (anag)" , "Stay (in position)" .)