Spooner understands badge is part of mast (5,4)
I believe the answer is:
crows nest
'spooner understands badge' is the definition.
I can't tell whether this defines the answer.
'part of mast' is the wordplay.
I cannot quite see how this works, but
'part' could be 'row' (row is a kind of part) and 'row' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'is' is the link.
Can you help me to learn more?
(Other definitions for crows nest that I've seen before include "elevated lookout platform" , "lookout post" , "high naval post" .)