Crossword Genius

Incidentally, it's beside the bright yellow Eton caps (2,3,3)

Ross

I believe the answer is:

by the bye

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

'incidentally' is the definition.
(synonyms)

'beside the bright yellow eton caps' is the wordplay.
'beside' becomes 'by'.
'bright yellow eton caps' becomes 'bye' (I can't justify this - if you can you should believe this answer much more).
'by'+'the'+'bye'='BY THE BYE'

'it's' acts as a link.

Can you help me to learn more?

(Other definitions for by the bye that I've seen before include "Incidentally" , "In passing" , "Parenthetically" .)

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