Prurient criminal is casual about love (9)
I believe the answer is:
salacious
'prurient' is the definition.
('salacious' can be a synonym of 'prurient')
'criminal is casual about love' is the wordplay.
'criminal' is an anagram indicator.
'about' is an insertion indicator.
'love' becomes 'o' (In tennis, 'love' means 'zero').
'is'+'casual'='iscasual'
'iscasual' anagrammed gives 'salacius'.
'salacius' placed around 'o' is 'SALACIOUS'.
(Other definitions for salacious that I've seen before include "Risque" , "Steamy" , "Arousing lustful thoughts" , "Lewd" , "Arousing lustful feelings" .)