Wild headlong rush (8)
I believe the answer is:
stampede
'wild headlong rush' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for stampede that I've seen before include "Panic-driven rush of herd of animals" , "Crazy pets made a sudden rush" , "collective flight" , "Sudden mad rush" , "Panic-stricken charge of cattle" .)