Spinner provided unwitting boundaries in the middle (10)
I believe the answer is:
centrifuge
'spinner' is the definition.
(machine which spins)
'provided unwitting boundaries in the middle' is the wordplay.
'provided' becomes 'if'.
'boundaries' means to remove the middle letters (only the edge or boundary letters remain).
'in the' indicates putting letters inside.
'middle' becomes 'centre' ('centre' can be a synonym of 'middle'**).
'unwitting' with its centre taken out is 'ug'.
'if'+'ug'='ifug'
'ifug' going within 'centre' is 'CENTRIFUGE'.
(Other definitions for centrifuge that I've seen before include "Rotating machine that separates particles" , "Spinner" .)