Leave no mark, concealing poison (5)

I believe the answer is:

venom

'poison' is the definition.
(I know that venom is a type of animal toxin)

'leave no mark concealing' is the wordplay.
'concealing' indicates a hidden word.
'VENOM' can be found hidden inside 'leave no mark'.

(Other definitions for venom that I've seen before include "Bitter malice" , "acrimony" , "Virulent feeling" , "Snake poison" , "bitterness" .)

I've seen this clue in The Times.

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