Argument, quarrel (7)
I believe the answer is:
dispute
I believe this clue is a double definition.
'argument' is the first definition.
(I've seen this before)
'quarrel' is the second definition.
(I know that quarrel can be written as dispute)
(Other definitions for dispute that I've seen before include "conflict" , "Disagree or challenge" , "Row" , "Altercate" , "Question or deny accuracy or validity" .)