She turns a nut (4)
I believe the answer is:
aunt
'she' is the definition.
('she' could refer to an aunt)
'turns a nut' is the wordplay.
'turns' indicates an anagram.
'a'+'nut'='anut'
'anut' is an anagram of 'AUNT'.
(Other definitions for aunt that I've seen before include "Parent's female sibling" , "Sister of father/mother" , "Family relative" , "Family member" , "Female relative" .)