Back-to-back (2,1,3)
I believe the answer is:
in a row
'back-to-back' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for in a row that I've seen before include "arguing?" , "Lined up" , "One after another" , "Paul --, Swiss artist" , "becoming involved in disturbance" .)