Forbid a socialite to have a hard heart (5)
I believe the answer is:
debar
'forbid' is the definition.
(I know that debar is a kind of forbid)
'a socialite to have a hard heart' is the wordplay.
'a socialite' becomes 'deb' (I have seen 'Young socialite ' mean 'deb' so perhaps 'socialite' could also mean 'deb').
'to have' means one lot of letters go next to another.
'heart' says to take the centre.
The centre of 'hard' is 'ar'.
'deb'+'ar'='DEBAR'
(Other definitions for debar that I've seen before include "Shut out, preclude" , "Exclude from a place" , "Prevent from doing something" , "Exclude (from right)" , "Ban" .)