Afterwards nearly everyone's on the side (7)
I believe the answer is:
lateral
'on the side' is the definition.
(I've seen this in another clue)
'afterwards nearly everyone's' is the wordplay.
'afterwards' becomes 'later' (synonyms).
'nearly' means to remove the last letter.
'everyone' becomes 'all' (all people).
'all' with its last letter removed is 'al'.
'later'+'al'='LATERAL'
(Other definitions for lateral that I've seen before include "belonging to the side" , "This kind of sideways thinking does not use conventional logic" , "Sidelong" , "Edgeways" , "Side branch" .)