First lady? Queen, always (4)
I believe the answer is:
ever
'always' is the definition.
('ever' can be a synonym of 'always')
'first lady? queen' is the wordplay.
'first' is a charade indicator (letters next to each other).
'lady?' becomes 'eve' (I've seen this before**).
'queen' becomes 'r' (r is abbreviation regina. e.g. in ER ).
'eve'+'r' is 'EVER'.
(Other definitions for ever that I've seen before include "Continually" , "To the end of time" , "At all times, always" , "Perpetually" , "Possibly" .)