Internal parts of radio spilled over surface (9)
I believe the answer is:
ellipsoid
'surface' is the definition.
(type of geometrical surface)
'internal parts of radio spilled over' is the wordplay.
'ELLIPSOID' is hidden backwards in amongst the letters.
However, I am uncertain how this is indicated.
(Other definitions for ellipsoid that I've seen before include "solid figure?" , "The earth is of this shape" .)