Go at it (4)
'go at it' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for spar that I've seen before include "Crystalline mineral" , "Wooden pole -- box" , "Stout pole, nautically" , "Mineral; box; wing beam" , "have an argument without marked hostility" .)
'go at it' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for argue that I've seen before include "Quarrel, bicker" , "Present reasons for or against" , "Squabble" , "Disagree violently" , "Contend with reasoning" .)