Comes upon unexpectedly when one lands (6)

I believe the answer is:

lights

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

'lands' is the definition.
(lighting is a kind of landing)

I cannot understand how the remainder of the clue works.

(Other definitions for lights that I've seen before include "Chances" , "SECOND PART OF 13" , "Ignites or illuminates" , "Innards" , "Illuminators; lungs" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app