First lady, Republican to the end (4)
I believe the answer is:
ever
'to the end' is the definition.
I can't judge whether this defines the answer.
'first lady republican' is the wordplay.
'first' is a charade indicator (letters next to each other).
'lady' becomes 'eve' (woman's name).
'republican' becomes 'R' (abbreviation in US politics).
'eve' next to 'r' is 'EVER'.
Can you help me to learn more?
(Other definitions for ever that I've seen before include "Continuously" , "Perpetually" , "constantly" , "To the end of time" , "Always, at any time" .)