Judge American officiating pole vault activity (7)
I believe the answer is:
jumping
'judge american officiating pole' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'vault activity' is the wordplay.
'vault' becomes 'jump' (vault can mean to jump).
'activity' becomes 'ing' (I can't explain this - if you can you should believe this answer much more).
'jump'+'ing'='JUMPING'
Can you help me to learn more?
(Another definition for jumping that I've seen is " Leaping, bounding".)