Aircraft windows letting in minimum of light (6)

I believe the answer is:

planes

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

'aircraft' is the definition.
(I've seen this in another clue)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for planes that I've seen before include "Aircraft and tools for smoothing wood" , "Those flying" , "Aircraft from Naples" , "Trees" , "Flat surface in Naples" .)

I've seen this clue in The Times.

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