Equipment includes new telephone (4)
I believe the answer is:
ring
'telephone' is the definition.
('ring' can be a synonym of 'telephone')
'equipment includes new' is the wordplay.
'equipment' becomes 'rig' (rig is a kind of equipment**).
'includes' indicates putting letters inside.
'new' becomes 'n'.
'rig' enclosing 'n' is 'RING'.
(Other definitions for ring that I've seen before include "Form circle around" , "Arena; jewellery item" , "Sound a doorbell" , "Encircle; arena" , "Phone; circle" .)