A quarrel about right marker (5)
I believe the answer is:
arrow
'marker' is the definition.
(I've seen this before)
'a quarrel about right' is the wordplay.
'a quarrel' becomes 'row' ('row' can be a synonym of 'quarrel').
'about' means one lot of letters go next to another.
'right' becomes 'ar' (I've seen this in other clues).
'row' put after 'ar' is 'ARROW'.
(Other definitions for arrow that I've seen before include "Archery projectile" , "Weapon projectile" , "Direction pointer" , "Missile in a quiver" , "broadly distinguishing old convict" .)