Weed spread under logs (9)
I believe the answer is:
groundsel
'weed' is the definition.
(I know that groundsel is a type of weed)
'spread under logs' is the wordplay.
'spread' is an anagram indicator.
'under'+'logs'='underlogs'
'underlogs' is an anagram of 'GROUNDSEL'.
(Other definitions for groundsel that I've seen before include "feed to the birds" , "Common weed" , "Plant of daisy family" , "plant, unwanted?" .)