Everyone securing three points in addition (2,4)
I believe the answer is:
as well
'in addition' is the definition.
(I've seen this before)
'everyone securing three points' is the wordplay.
'everyone' becomes 'all' (all people).
'securing' indicates putting letters inside.
'three points' becomes 'SWE'.
'all' placed around 'swe' is 'AS WELL'.
(Other definitions for as well that I've seen before include "on top" , "Also, in addition" , "with equal effect" , "A swell sort of addition" , "Also, additionally" .)