Devious spy to go legit - perhaps Carter? (12)
I believe the answer is:
egyptologist
'perhaps carter?' is the definition.
(Howard Carter excavated Tutankhamun's tomb)
'devious spy to go legit' is the wordplay.
'devious' indicates an anagram.
'spy'+'to'+'go'+'legit'='spytogolegit'
'spytogolegit' with letters rearranged gives 'EGYPTOLOGIST'.
(Other definitions for egyptologist that I've seen before include "One such as Flinders Petrie or Howard Carter" , "Carter eg" .)