Disagreements in the ranks (4)
I believe the answer is:
rows
I believe this is a double definition.
'disagreements' is the first definition.
(row is a kind of disagreement)
'the ranks' is the second definition.
(rank can mean a row or line of things)
'in' acts as a link.
(Other definitions for rows that I've seen before include "Tiers" , "Uses oars" , "Propels into quarrels?" , "emotional exchanges" , "Disagreements" .)