Poles surround complete eccentrics (7)
I believe the answer is:
nutters
'eccentrics' is the definition.
(I know this)
'poles surround complete' is the wordplay.
'poles' becomes 'NS' (north and south poles).
'surround' means one lot of letters goes inside another.
'complete' becomes 'utter' (both can mean total).
'ns' enclosing 'utter' is 'NUTTERS'.
(Other definitions for nutters that I've seen before include "Crazy people (slang)" , "Test run for crazy or eccentric people" , "Crazy folk" , "Crazy people (sl.)" .)