Collapse of steep dam results in mad rush (8)
I believe the answer is:
stampede
'mad rush' is the definition.
(I've seen this in another clue)
'collapse of steep dam' is the wordplay.
'collapse of' indicates anagramming the letters.
'steep'+'dam'='steepdam'
'steepdam' anagrammed gives 'STAMPEDE'.
'results in' acts as a link.
(Other definitions for stampede that I've seen before include "Put to flight" , "Sudden rush of a panicstricken herd" , "Sudden dash of a group of startled animals" , "Headlong rush of a group in panic" , "uncontrolled flight" .)