Person involved in assassination in Japan? (5)
I believe the answer is:
ninja
'person involved in assassination in japan?' is the definition.
I know that 'japan' relates to this answer.
'in assassination in japan?' is the wordplay.
'in' indicates a hidden word.
'NINJA' is hidden in the letters of 'assassination in japan'.
(Other definitions for ninja that I've seen before include "Fourteenth-century Japanese assassin" , "Deadly type" , "Japanese expert in stealth and martial arts" , "Assassins" , "Former mercenary" .)