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 before)

I cannot understand how the rest of the clue works.

(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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