What a 50 amp bulb produces (9)

I believe the answer is:

lamplight

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'what a 50 amp bulb produces' is the definition.
I can't tell whether this defines the answer.

'what a 50 amp bulb' is the wordplay.
'what a 50' becomes 'l' (Roman numeral).
'bulb' becomes 'light bulb' (synonyms).
'l'+'amp'+'light'='LAMPLIGHT'

Can you help me to learn more?

(Other definitions for lamplight that I've seen before include "Ray perhaps" , "David Essex recording" , "It illuminates" , "which is illuminating" , "Illumination" .)

I've seen this clue in The Globe and Mail.

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