Catch on to a branch (4)

I believe the answer is:

twig

I believe this is a double definition.

'catch on' is the first definition.
(synonyms)

'branch' is the second definition.
(I know that twig is a more specific form of the action branch)

'to a' acts as a link.

(Other definitions for twig that I've seen before include "Suddenly see; branchlet" , "a small piece of gum?" , "Suddenly realise" , "Small woody shoot" , "Small tree shoot" .)

I've seen this clue in the Evening Standard.

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