Locate stand-in turning up in row (4-2)
I believe the answer is:
Here is my best explanation:
'row' is the definition.
(bust-up is a kind of row)
'locate stand-in turning up' is the subsidiary indication.
'locate' becomes 'put'.
'stand in' becomes 'sub' ('sub' can be a synonym of 'stand in').
'turning up' says the letters should be written in reverse.
'putsub' backwards is 'bustup'.
'in' is the link.
(Other definitions for bust-up that I've seen before include "disagreement", "Serious quarrel/fight", "Argument finishing a relationship", "Quarrel, brawl", "Serious quarrel or fight (B, not D)", "Quarrel, possibly ending a friendship" and "Serious altercation".)