Extravagantly advertise capers, spinning additional dimension (10)
I believe the answer is:
hyperspace
'additional dimension' is the definition.
The definition suggests a singular noun which matches the answer. I also know that 'dimension' relates to this answer.
'extravagantly advertise capers spinning' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'capers' is 'erspac' which is within the answer.
The remaining letters 'hype' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for hyperspace that I've seen before include "An area of sci-fi" , "Imagined environment with more than three dimensions" , "(In sci-fi) the fourth dimension" , "Region with more than three dimensions" .)