Kind of well (8)
I believe the answer is:
artesian
'kind of well' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for artesian that I've seen before include "A nastier sort of well, oddly" , "(Well) fed by pressure" , "Type of well that doesn't need a pump" , "(Well) flowing under natural pressure" , "Type of deep well" .)