Poison scare in stews (7)
I believe the answer is:
arsenic
'poison' is the definition.
(thesaurus)
'scare in stews' is the wordplay.
'stews' indicates anagramming the letters.
'scare'+'in'='scarein'
'scarein' with letters rearranged gives 'ARSENIC'.
(Other definitions for arsenic that I've seen before include "-- and Old Lace (play)" , "Poison used in pesticides and weedkillers" , "As briefly identified" , "Poison found in races" , "Toxic metalloid element" .)