It can result when many stampede (5)
I believe the answer is:
crush
'it can result' is the definition.
The definition suggests a singular noun which matches the answer.
'many stampede' is the wordplay.
'many' becomes 'c' (C is the Roman numeral for r00).
'stampede' becomes 'rush' (I've seen this before).
'c'+'rush'='CRUSH'
'when' acts as a link.
Can you help me to learn more?
(Other definitions for crush that I've seen before include "An infatuation with the orange drink?" , "Squash" , "Close crowd of people" , "Steamroller" , "Deform; violently subdue (rebellion)" .)