Scheme that initially works (5)
I believe the answer is:
plant
'works' is the definition.
('plant' can be a synonym of 'works')
'scheme that initially' is the wordplay.
'scheme' becomes 'plan' (I've seen this before).
'initially' suggests taking the first letters.
The first letter of 'that' is 't'.
'plan'+'t'='PLANT'
(Other definitions for plant that I've seen before include "Factory; establish" , "Growing organism - industrial buildings" , "Snooker shot; factory" , "Machinery; spy" , "Factory; informer" .)