Pole in space; a scene of much action (5)
I believe the answer is:
arena
'scene of much action' is the definition.
'arena' can be an answer for 'scene' (I've seen this before). I am unsure of the 'of much action' bit.
'pole in space a' is the wordplay.
'pole in' becomes 'ar' (I can't explain this - if you can you should give a lot more credence to this answer).
'space' becomes 'en' (in printing, a space as wide as a letter 'n').
'ar'+'en'+'a'='ARENA'
Can you help me to learn more?
(Other definitions for arena that I've seen before include "Battleground" , "Where gladiators fought" , "sports ground" , "Amphitheatre's central space" , "Entertainments venue" .)