Fabulous flier from Rochdale (3)

I believe the answer is:

roc

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

'fabulous flier' is the definition.
(I've seen this in another clue)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for roc that I've seen before include "Vast legendary bird" , "Giant mythical bird" , "Gigantic bird of eastern legend - cor!" , "Bird imagined" , "Gigantic bird of Arabian legend" .)

I've seen this clue in the Evening Standard.

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