Crossword Genius

Iron left on? That’s criminal (5)

Ross

I believe the answer is:

felon

'criminal' is the definition.
('felon' can be a synonym of 'criminal')

'iron left on?' is the wordplay.
'iron' becomes 'fe' (Fe is the chemical symbol for iron).
'left' becomes 'l' (common abbreviation).
'fe'+'l'+'on'='FELON'

'thats' acts as a link.

(Other definitions for felon that I've seen before include "criminal from Texas" , "Law-breaker" , "Has conviction" , "Serious criminal" , "Malefactor" .)

I've seen this clue in The Telegraph.
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