Energy firm recruits city guide — it could spark something off (4,6)

I believe the answer is:

fire hazard

'it could spark something off' is the definition.

'energy firm recruits city guide' is the wordplay.
'energy' becomes 'fire'.
'firm' becomes 'hard' ('hard' can be similar in meaning to 'firm').
'recruits' indicates putting letters inside.
'city guide' becomes 'az' (A-Z, UK street atlas brand).
'hard' going around 'az' is 'hazard'.
'fire'+'hazard'='FIRE HAZARD'

I've seen this clue in The Guardian.

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