Organ division (4)
I believe the answer is:
'organ division' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for lobe that I've seen before include "could be site of a 24 [STUD]" , "Piece of ear" , "Rounded part (of organ)" , "Lower part of the ear" , "Base of ear" .)