Top half of planet seen by Jack somewhere in the Hebrides (4)
I believe the answer is:
jura
'top' is the definition.
Both the answer and definition are singular nouns.
Perhaps there's a link between them I don't understand?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for jura that I've seen before include "island > range" , "European mountain range" , "Inner Hebridean isle" , "Inner Hebrides island" , "Inner Hebrides isle" .)