Runs slip away causing setback (7)
I believe the answer is:
relapse
'setback' is the definition.
(thesaurus)
'runs slip away' is the wordplay.
'runs' becomes 'r' (cricket abbreviation).
'slip away' becomes 'elapse' ('elapse' can be a synonym of 'slip away').
'r'+'elapse'='RELAPSE'
'causing' acts as a link.
(Other definitions for relapse that I've seen before include "fall into sin" , "Decline" , "Return to sickness" , "Unexpected deterioration" , "Fall back like leapers" .)