Bet and Sara may be side by side (7)
I believe the answer is:
abreast
'side by side' is the definition.
(synonyms)
'bet and sara may be' is the wordplay.
'and' is a charade indicator (letters next to each other).
'may be' is an anagram indicator.
'bet'+'sara'='betsara'
'betsara' anagrammed gives 'ABREAST'.
(Other definitions for abreast that I've seen before include "to be up to date" , "Side by side - in the picture" , "Well-informed" , "Level in line" , "shoulder to shoulder" .)