Republican female reflected: 'Trump essentially a one-time leader' (5)
I believe the answer is:
nehru
'a one-time leader' is the definition.
(Jawaharlal Nehru, Indian prime minister)
'republican female reflected trump essentially' is the wordplay.
'republican' becomes 'r' (abbreviation).
'female' becomes 'hen' (hen is a kind of female).
'reflected' says the letters should be written in reverse.
'essentially' says to take the centre.
The middle letter of 'trump' is 'u'.
'r'+'hen'='rhen'
'rhen' written backwards gives 'nehr'.
'nehr'+'u'='NEHRU'
(Other definitions for nehru that I've seen before include "former statesman" , "Indian statesman" , "Pandit . . . . ., former Indian Prime Minister" , "Jawaharlal -, first PM of India" , "Student of Gandhi" .)