Plant found in bog round Sellafield (9)
I believe the answer is:
groundsel
'plant' is the definition.
(groundsel is a kind of plant)
'in bog round sellafield' is the wordplay.
'in' indicates the answer is hidden within the clue.
'GROUNDSEL' is hidden in the letters of 'bog round sellafield'.
'found' is the link.
(Other definitions for groundsel that I've seen before include "Common weed" , "feed to the birds" , "Plant of daisy family" , "plant, unwanted?" .)