Being out of EEC isn’t unusual (9)
I believe the answer is:
existence
'being' is the definition.
('existence' can be a synonym of 'being')
'out of eec isn't unusual' is the wordplay.
'out of' becomes 'ex'.
'unusual' indicates anagramming the letters.
'eec'+'isnt'='eecisnt'
'eecisnt' with letters rearranged gives 'istence'.
'ex'+'istence'='EXISTENCE'
(Other definitions for existence that I've seen before include "A way of living" , "State of being" , "survival" , "The business of being" , "Way of life" .)