Wild flower absorbing nitrogen (7)
I believe the answer is:
violent
'wild' is the definition.
(I know that wild can be written as violent)
'flower absorbing nitrogen' is the wordplay.
'flower' becomes 'violet' (I've seen this before).
'absorbing' indicates putting letters inside.
'nitrogen' becomes 'N' (N is the chemical symbol for nitrogen).
'violet' placed around 'n' is 'VIOLENT'.
(Other definitions for violent that I've seen before include "Hot-headed" , "Intensely forcible" , "Bloodthirsty" , "Using excessive force" , "Strong - destructive" .)