Fear of open spaces (11)
I believe the answer is:
agoraphobia
'fear of open spaces' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for agoraphobia that I've seen before include "Morbid fear of open spaces" , "Fear of being in public places" , "Fear of outdoors" , "Morbid fear of open places" .)