Statistically essential? (5)
I believe the answer is:
vital
'essential?' is the definition.
('vital' can be similar in meaning to 'essential')
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for vital that I've seen before include "Essential to life or critically important" , "Are such statistics" , "Absolutely necessary or life-giving" , "Critical, necessary" , "Essential; lively" .)