It's lower without iodine? In no case! (7)
I believe the answer is:
neither
'in no case' is the definition.
(in neither case)
'it's lower without iodine?' is the wordplay.
'it's lower' becomes 'nether' (as in nether regions).
'without' indicates putting letters inside ('without' can be similar in meaning to 'outside').
'iodine?' becomes 'I' (chemical symbol).
'nether' going around 'i' is 'NEITHER'.
(Other definitions for neither that I've seen before include "And not; nor yet" , "Therein (anag)" , "both are rejected" , "In three (anag.)" , "The rein (anag.)" .)