Trump's reserve money? (5)
I believe the answer is:
pence
I believe this clue is a double definition.
'trump's reserve' is the first definition.
(Mike Pence, Donald Trump's vice president)
'money?' is the second definition.
(I've seen this before)
(Other definitions for pence that I've seen before include "Small sum of money" , "President's vice" , "some European capital" , "Money used to be pounds, shillings and ....." , "Small coppers" .)