Fifty-fifty splitting two hundred? It's criminal (7)
I believe the answer is:
illicit
'criminal' is the definition.
(I've seen this before)
'fifty-fifty splitting two hundred? it's' is the wordplay.
'fifty-fifty' becomes 'LL' (L is 50 in Roman numerals).
'splitting' indicates putting letters inside (some letters split a word into two).
'two' becomes 'II' (Roman numerals).
'hundred?' becomes 'c' (Roman numeral).
'll' going within 'ii' is 'illi'.
'illi'+'c'+'it'='ILLICIT'
(Other definitions for illicit that I've seen before include "criminal" , "Contrary to morality or convention" , "breaking the rules" , "Without approval" , "Forbidden by law, rules" .)