Essential in reduced scheme involving insurance (9)
I believe the answer is:
intrinsic
'essential' is the definition.
(associated in meaning)
'in reduced scheme involving insurance' is the wordplay.
'reduced scheme' becomes 'tric' (I can't justify this - if you can you should believe this answer much more).
'involving' is an insertion indicator.
'insurance' becomes 'ins' (business abbreviation).
'tric' placed around 'ins' is 'trinsic'.
'in'+'trinsic'='INTRINSIC'
Can you help me to learn more?
(Other definitions for intrinsic that I've seen before include "Belonging as an inherent and essential part" , "Genuine" , "Of the essential nature of something" , "Natural" , "native?" .)