Fighting side by side? (2,1,3)
I believe the answer is:
in a row
'fighting' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for in a row that I've seen before include "running" , "Consecutively" , "Like all the pretty maids" , "Lined up" , "arguing?" .)