We name it as groundsel, say (4)
I believe the answer is:
weed
'groundsel say' is the definition.
(groundsel is a kind of weed)
'we name' is the wordplay.
'name' becomes 'ed' (short for edward).
'we'+'ed'='WEED'
'it as' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for weed that I've seen before include "Intrusive plant; weak person" , "Useless plant - useless person" , "Got rid of water" , "dope" , "Work in garden" .)