Shoulder-to-shoulder (7)
I believe the answer is:
abreast
'shoulder-to-shoulder' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for abreast that I've seen before include "Side by side; keeping pace" , "On a level together" , "Familiar" , "acquainted" , "Alongside one another and facing the same way" .)