Arousal from online pursuit? (9)

I believe the answer is:
evocation
'arousal' is the definition.
(thesaurus)
'from online pursuit?' is the wordplay.
I cannot quite understand how this works, but
'from' could be 'o' (I've seen this in other clues) and 'o' is present in the answer.
'online' could be 'on' (similar in meaning) and 'on' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for evocation that I've seen before include "A spell" , "A calling forth" .)