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