Crossword Genius

Rib and rib-tickling twit (9)

Ross

I believe the answer is:

birdbrain

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

'twit' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps you can see a link between them that I don't see?

'rib and rib-tickling' is the wordplay.
'rib and rib' anagrams to 'BIRDBRAIN'.
However, I am unsure how this is indicated.

Can you help me to learn more?

(Other definitions for birdbrain that I've seen before include "Twittering twit?" , "Fool" , "Stupid" , "Silly person (with sparrow's mind?)" .)

I've seen this clue in the Sydney Morning Herald.
Want a hint initially instead of a full solution? Install my app