Minister in PA (4,9)
I believe the answer is:
home secretary
'minister' is the definition.
(Home Secretary is an example)
'in pa' is the wordplay.
'in' becomes 'home' ('he's in' can mean 'he's home').
'pa' becomes 'secretary' (PA can mean personal assistant).
'home'+'secretary'='HOME SECRETARY'
(Other definitions for home secretary that I've seen before include "Government minister" , "member of the cabinet" , "Minister for internal affairs" , "Cabinet position" , "Tory era scheme (anag) - Cabinet minister" .)