Official getting entire gist: rarely only partially (9)
I believe the answer is:
registrar
'official' is the definition.
(registrar is a kind of official)
'entire gist rarely only partially' is the wordplay.
'only partially' indicates a hidden word.
'REGISTRAR' is hidden within 'entire gist rarely'.
'getting' is the link.
(Other definitions for registrar that I've seen before include "University administrator -- hospital doctor" , "Record keeper - hospital doctor" , "Official recording births, deaths and marriages" , "Medic" , "Official record keeper" .)