First Lady supported by Republican at all times (4)
I believe the answer is:
ever
'at all times' is the definition.
('ever' can be a synonym of 'at all times')
'first lady supported by republican' is the wordplay.
'first lady' becomes 'eve' (I've seen this before).
'supported by' is a charade indicator (letters next to each other) (letters go below - in down clue).
'republican' becomes 'r' (abbreviation).
'eve'+'r'='EVER'
(Other definitions for ever that I've seen before include "Continually" , "Eternally" , "Always, at any time" , "Continuously" , "Veer away endlessly" .)