First of children interrupting motorcyclist to argue (6)
I believe the answer is:
bicker
'argue' is the definition.
(bickering is a kind of arguing)
'first of children interrupting motorcyclist' is the wordplay.
'first of children' becomes 'c' (1st letter of 'children').
'interrupting' is an insertion indicator.
'motorcyclist' becomes 'biker' (I've seen this before).
'c' going into 'biker' is 'BICKER'.
'to' is the link.
(Other definitions for bicker that I've seen before include "Argue pettily" , "Row" , "Petty argument" , "Squabble" , "Quarrel about unimportant things" .)