Gather undoctored author lacks English (4)

I believe the answer is:

suss

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'gather' is the definition.
(as in sussing something out or gathering it)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for suss that I've seen before include "Divine nature of" , "sharpness of mind" , "Figure (out)" , "Work (out) (slang)" , "Realise (informal)" .)

I've seen this clue in The Guardian.

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