Poison scare in ground (7)
I believe the answer is:
arsenic
'poison' is the definition.
(arsenic can be used as a poison)
'scare in ground' is the wordplay.
'ground' indicates anagramming the letters ('grind' the letters into a new form).
'scare'+'in'='scarein'
'scarein' is an anagram of 'ARSENIC'.
(Other definitions for arsenic that I've seen before include ", it goes with old lace" , "Powerful poison" , "Toxic metallic element used as rat poison" , "Can rise result from poison?" , "Poison found in races" .)