Align, informally (4)
I believe the answer is:
sync
'align informally' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sync that I've seen before include "Togetherness (of sound and picture, say)" , "Relationship when things occur at the same time" , "In which things occur simultaneously" , "Agreement in time" , "go together" .)