Root and branch from wide shrub (6)
I believe the answer is:
wholly
'root' is the definition.
(thesaurus)
'wide shrub' is the wordplay.
'wide' becomes 'w' (abbreviation e.g. in cricket).
'shrub' becomes 'holly' (I have seen 'Prickly shrub ' mean 'holly' so perhaps 'shrub' could also mean 'holly').
'w'+'holly'='WHOLLY'
'and branch from' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for wholly that I've seen before include "Absolutely!" , "One hundred per cent" , "in every respect" , "Entirely, fully" , "in every area" .)