Spot threat to crops – time to get away (5)

I believe the answer is:

locus

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

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

I don't understand the remainder of the clue.

(Other definitions for locus that I've seen before include "a result of a certain formula" , "line" , "insect" , "Spot" , "Exact place of something" .)

I've seen this clue in The Guardian.

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