Zane Grey - occasionally visionary (4)

I believe the answer is:
aery
'visionary' is the definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?
'zane grey occasionally' is the wordplay.
'occasionally' means one should take alternating letters (letters taken at regular intervals or occasions).
'zane'+'grey'='zanegrey'
The alternating letters of 'zanegrey' are 'AERY'.
Can you help me to learn more?
(Other definitions for aery that I've seen before include "high place" , "ethereal" , "spiritual" .)
