Have no mercy showing spite (5)

I believe the answer is:

venom

'spite' is the definition.
(I've seen this before)

'have no mercy showing' is the wordplay.
'showing' says the answer is hidden in the clue.
'VENOM' can be found hidden inside 'have no mercy'.

(Other definitions for venom that I've seen before include "Poison - spite" , "acrimony" , "Poisonous secretion" , "ill will" , "bitterness" .)

I've seen this clue in The Telegraph.

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