Curtail Spooner's farewell (6-3)
I believe the answer is:
toodle-pip
'farewell' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for toodle-pip that I've seen before include "Goodbye (dated)" , "so long" , "Farewell remark - dipole top (anag)" , "Take care" , "Farewell (informal)" .)