About one oddly intense Genius (8)
I believe the answer is:
einstein
'genius' is the definition.
(as in Albert Einstein)
'about one oddly intense' is the wordplay.
'about' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'oddly' indicates anagramming the letters.
'intense' with letters rearranged gives 'enstein'.
'i' inserted within 'enstein' is 'EINSTEIN'.
(Other definitions for einstein that I've seen before include "Bavarian" , "Famous scientist of the nineties" , "Famous physicist, mathematician" , "Brilliant scientist" , "German expert on relativity" .)