Cover conflict, speaking intemperately? (8)
I believe the answer is:
Here is my best explanation:
'cover' is the definition.
(warranty cover is a type of insurance)
'conflict speaking intemperately?' is the subsidiary indication.
'conflict' becomes 'war' (war is a kind of conflict).
'speaking intemperately?' becomes 'ranty'.
(Other definitions for warranty that I've seen before include "Guarantee given to a purchaser", "Written guarantee", "Free repair document", "Undertaking (as to quality)", "Certificate", "Undertaking that covers sale" and "Quality guarantee".)