A majority (4)
I believe the answer is:
most
'a majority' is the definition.
(most of a group)
This is the entire clue.
(Other definitions for most that I've seen before include "Kind of commercial pact where two countries agree to treat each other as well as any other" , "In the highest degree" , "Extremely, very" , "Nearly all, majority" , "Greatest in amount or degree" .)