Allied (5)
'allied' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sided that I've seen before include "Showed solidarity (with)" , "Allied oneself (with one party)" , "Took part with person in a dispute" .)
'allied' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for united that I've seen before include "Joined into a single entity" , "Joined or combined" , "Made one" , "Of one mind" , "Merged into one" .)