"put your foot down" (10)
'foot down' is the definition.
'tread' can be an answer for 'foot' (treading is a kind of footing). I'm not certain of the 'down' bit.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for tread that I've seen before include "Top surface of a stair step" , "between the car and the road" , "Sole of a shoe" , "way of dancing" , "Put one's foot down!" .)
(Other definitions for accelerate that I've seen before include "Crank up" , "Increase speed" , "snowball" , "Quicken" , "Go faster" .)
'put your foot down?' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for step that I've seen before include "Second half of quick 20?" , "A pace for pets" , "Pace (taken one at a time?)" , "Stage - pace" , "Rung, dance movement" .)