Set up company with new number (9)
I believe the answer is:
configure
'set up' is the definition.
(configuring is a kind of setting up)
'company with new number' is the wordplay.
'company' becomes 'co' (abbreviation).
'with' says to put letters next to each other.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'number' becomes 'figure' (figure is a kind of whole number).
'co'+'n'+'figure'='CONFIGURE'
(Other definitions for configure that I've seen before include "Arrange (something) to fit a particular task" , "Set up" , "Make arrangement" .)