Training run and jog Ben has in city (12)
I believe the answer is:
johannesburg
'city' is the definition.
(I've seen this before)
'training run and jog ben has' is the wordplay.
'training' indicates an anagram (to train can mean to grow something into a shape).
'and' says to put letters next to each other.
'run'+'jog'+'ben'+'has'='runjogbenhas'
'runjogbenhas' is an anagram of 'JOHANNESBURG'.
'in' acts as a link.
(Other definitions for johannesburg that I've seen before include "South African city" , "Largest S. African city" .)