Time will certainly not stand still! (5)
I believe the answer is:
march
'time' is the definition.
The answer and definition can be both related to time as well as being singular nouns.
Maybe they are linked in a way I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for march that I've seen before include "Month, piece of music" , "Journey undertaken by army etc" , "make progress" , "The month for military movement" , "Proceed in procession" .)