First lady with Queen, always (4)
I believe the answer is:
ever
'always' is the definition.
(synonyms)
'first lady with queen' is the wordplay.
'first lady' becomes 'eve' (Biblical first woman).
'with' says to put letters next to each other.
'queen' becomes 'r' (abbreviation for regina, e.g. in ER ).
'eve'+'r'='EVER'
(Other definitions for ever that I've seen before include "Eternity" , "Veer away endlessly" , "Perpetually" , "In perpetuity" , "At all times, always" .)