Barren piece of nuclear ideology (4)
I believe the answer is:
arid
'barren' is the definition.
(I've seen this in another clue)
'piece of nuclear ideology' is the wordplay.
'piece of' says the answer is hidden in the clue.
'ARID' is hidden within 'nuclear ideology'.
(Other definitions for arid that I've seen before include "Excessively dry" , "Extremely dry" , "Dry raid" , "Dry and sere" , "Dry, devoid of interest" .)