Hitman in Jamaica concealing another killer (5)

I believe the answer is:

ninja

I'm a little stuck... Click here to teach me more about this clue!

'another killer' is the definition.
'ninja' can be an answer for 'killer' (I've seen this before). I am unsure of the 'another' bit.

'hitman in jamaica concealing' is the wordplay.
'concealing' says the answer is hidden in the clue.
'NINJA' is hidden in the letters of 'hitman in jamaica'.

Can you help me to learn more?

(Other definitions for ninja that I've seen before include "Japanese expert in stealth and martial arts" , "Japanese mercenary warrior" , "Japanese assassin/spy" , "Person skilled in Japanese martial art" , "Former mercenary" .)

I've seen this clue in The Times.

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