Cotton on small shoot (4)

I believe the answer is:

twig

I believe this clue is a double definition.

'cotton on' is the first definition.
(both can mean to realise something)

'small shoot' is the second definition.
(I've seen this in another clue)

(Other definitions for twig that I've seen before include "Suddenly catch" , "bit of wood" , "Tiny end of branch" , "Latch on" , "Small woody shoot" .)

I've seen this clue in The Times.

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