President Macron's rejection holds team back (5)
I believe the answer is:
nixon
'president' is the definition.
(Richard Nixon)
'macron's rejection holds team back' is the wordplay.
'macron's rejection' becomes 'non' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'holds' indicates putting letters inside.
'team' becomes 'XI' (a football team, from Roman numerals for nn).
'back' shows that the letters should be reversed in order.
'non' enclosing 'xi' is 'noxin'.
'noxin' backwards is 'NIXON'.
Can you help me to learn more?
(Other definitions for nixon that I've seen before include "37th US President" , "Only US president to resign" , "Former US president" , "Richard -, US president who resigned in nineteen seventy four" , "Watergate was his downfall" .)