Running a race, let rip (8)
I believe the answer is:
lacerate
'rip' is the definition.
(I've seen this before)
'running a race let' is the wordplay.
'running' is an anagram indicator.
'a'+'race'+'let'='aracelet'
'aracelet' anagrammed gives 'LACERATE'.
(Other definitions for lacerate that I've seen before include "Tear or gash roughly" , "Tear, wound, hurt" , "Injure be tearing, wound roughly" , "Deeply cut (flesh, skin)" , "Cut or tear irregularly" .)