A hill in Pretoria (3)
I believe the answer is:
tor
'a hill' is the definition.
(tor is a kind of hill)
'in pretoria' is the wordplay.
'in' indicates a hidden word.
'TOR' can be found hidden inside 'pretoria'.
(Other definitions for tor that I've seen before include "Rot on a hill in Cornwall" , "feature of Glastonbury" , "Fermenting agent" , "Rot about the rocky height" , "Dartmoor peak" .)