Beat off a gathering of people (5)
I believe the answer is:
outdo
'beat' is the definition.
(outdoing is a kind of beating)
'off a gathering of people' is the wordplay.
'off' becomes 'out'.
'a gathering of people' becomes 'do'.
'out'+'do'='OUTDO'
(Other definitions for outdo that I've seen before include "Eclipse" , "Surpass, go one better than" , "Beat" , "Perform better than surpass" , "Be better in performance (than another person)" .)