Blame one bizarre fertiliser (8)
I believe the answer is:
bonemeal
'fertiliser' is the definition.
(I have seen 'Organic fertiliser' mean 'bonemeal' so perhaps 'fertiliser' could also mean 'bonemeal')
'blame one bizarre' is the wordplay.
'bizarre' indicates an anagram.
'blame'+'one'='blameone'
'blameone' with letters rearranged gives 'BONEMEAL'.
(Other definitions for bonemeal that I've seen before include "Type of fertiliser" , "Organic fertiliser" .)