There's ultimately room all round in such open spaces (5)
I believe the answer is:
moors
'spaces' is the definition.
Although both the answer and definition are verbs in their -s form, I cannot understand how they can define each other.
'there's ultimately room all round in such open' is the wordplay.
'there's' is a charade indicator (letters next to each other).
'ultimately' indicates one should take the final letters.
'all round in' becomes 'oor' (I can't explain this - if you can you should give a lot more credence to this answer).
'open' says to take the initial letters (I've seen 'opens' mean this).
The final letter of 'room' is 'm'.
The first letter of 'such' is 's'.
'm' next to 'oor' is 'moor'.
'moor'+'s'='MOORS'
Can you help me to learn more?
(Other definitions for moors that I've seen before include "Ties up (vessel)" , "wild areas" , "wild places" , "Ties up a boat" , "Conquerors once" .)