Campaigns for used cars to be serviced (8)
I believe the answer is:
crusades
'campaigns' is the definition.
(Crusade is an example)
'used cars to be serviced' is the wordplay.
'to be serviced' is an anagram indicator (to service can mean to repair).
'used'+'cars'='usedcars'
'usedcars' anagrammed gives 'CRUSADES'.
'for' is the link.
(Other definitions for crusades that I've seen before include "wars" , "Military expeditions by Christians to recapture the Holy Land" .)