Put one's foot down? Minister's revolting (3,2)
I believe the answer is:
rev up
'put one's foot down?' is the definition.
(as in to rev a car)
'minister's revolting' is the wordplay.
'minister' becomes 'rev' (I've seen this in other clues).
'revolting' becomes 'up' (I've seen this in other clues).
'rev'+'up'='REV UP'
(Other definitions for rev up that I've seen before include "Press accelerator" , "Increase the engine speed" , "To create excitement" , "drive to go faster" , "Accelerate sharply" .)