Coming from the orchard, spotted Arabian losing the head (5)
I believe the answer is:
apple
'head' is the definition.
The definition and answer can be both plants as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for apple that I've seen before include "Fruit that keeps doctor away?" , "Fruit from Eden?" , "Pink Lady, for example" , "Tree of the rose family" , "Fruit used in cider" .)