A head unearthed in the garden? (6)
I believe the answer is:
celery
'a head' is the definition.
The answer and definition can be both plants as well as being singular nouns.
Perhaps there's a link between them I don't understand?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for celery that I've seen before include "Vegetable with crisp stalks" , "Expedition" , "The crunch matter for slimmer" , "Its leaf stalks are used in salads or as a vegetable" , "Leafstalks eaten as a vegetable" .)