Assertion, contention (5)
I believe the answer is:
claim
I believe this is a double definition.
'assertion' is the first definition.
(I know that claim is a type of assertion)
'contention' is the second definition.
(I've seen this in another clue)
(Other definitions for claim that I've seen before include "Take" , "Right; demand this" , "Cause the loss of (a life)" , "Assertion; demand" , "Allegation" .)