Array (3)
I believe the answer is:
set
'array' is the definition.
(I know that array is a more specific form of the action arrange)
This is all the clue.
(Other definitions for set that I've seen before include "Determined or congealed" , "Cake < , plonk < , something served" , "Firm, like jelly" , "Put, coagulate" , "Gel; group" .)