GP (6,6)
There are a few possibilities for this:
family doctor
'gp' is the definition.
(family doctor is a kind of gp)
This is all the clue.
'gp' is the definition.
(I've seen this in other clues)
This is the entire clue.
(Other definitions for doc that I've seen before include "Medical practitioner (abbr)" , "Disney dwarf" , "Medic (colloq.)" , "scaled-down version of GP" , "Medic (familiar)" .)