Stride number about crush (4,2)
I believe the answer is:
step on
'crush' is the definition.
(I've seen this before)
'stride number about' is the wordplay.
'stride' becomes 'step' (synonyms).
'number' becomes 'no' (abbreviation).
'about' says the letters should be written in reverse.
'no' back-to-front is 'on'.
'step'+'on'='STEP ON'
(Other definitions for step on that I've seen before include "Behave harshly towards" , "crush" .)