Crossword Genius

Army regulation requires something to fix bright light (3-4)

Ross

I believe the answer is:

arc-lamp

I'm a little stuck... Click here to teach me more about this clue!

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

'army regulation requires something to fix' is the wordplay.
I cannot really understand how this works, but
'fix' could be 'clamp' (clamping is a kind of fixing) and 'clamp' is located in the answer.
The remaining letters 'ar' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in The Independent.
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