Polite conflict? Hardly! (5,3)
I believe the answer is:
civil war
'polite conflict? hardly' is the definition.
I can't judge whether this definition defines the answer.
'polite conflict?' is the wordplay.
'polite' becomes 'civil' (synonyms).
'conflict?' becomes 'war' (war is a kind of conflict).
'civil'+'war'='CIVIL WAR'
Can you help me to learn more?
(Other definitions for civil war that I've seen before include "Internecine strife within a country" , "Internal or fratricidal strife in a country" , "A fratricidal conflict of national dimension" , "Internal conflict within country" , "power struggle" .)