Crossword Genius

Possible killer on board, clue so hot? (4,6)

Ross

I believe the answer is:

lead piping

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

'possible killer on board' is the definition.
I can't tell whether this definition defines the answer.

'clue so hot?' is the wordplay.
'clue' becomes 'lead' (I've seen this before).
'so hot?' becomes 'piping' (I can't justify this - if you can you should give a lot more credence to this answer).
'lead'+'piping'='LEAD PIPING'

Can you help me to learn more?

(Another definition for lead piping that I've seen is " Old Cluedo weapon".)

I've seen this clue in The Guardian.
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