Whale of a show, initially? (5)

I believe the answer is:

pilot

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

'whale' is the definition.
(pilot whale is a kind of whale)

I cannot understand how the rest of the clue works.

(Other definitions for pilot that I've seen before include "Plane flier" , "-- Whale; -- light" , "One who brings a vessel into port" , "Flier or helmsman" , "Navigator" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app