First Lady meeting resistance at all times (4)
I believe the answer is:
ever
'at all times' is the definition.
(synonyms)
'first lady meeting resistance' is the wordplay.
'first lady' becomes 'eve' (first woman in the Bible).
'meeting' means one lot of letters go next to another.
'resistance' becomes 'r' (electronics abbreviation).
'eve'+'r'='EVER'
(Other definitions for ever that I've seen before include "Always and permanent" , "Eternally" , "Possibly" , "To the end of time" , "At all times, always" .)