Junior doctor for Bury and Wigan at last (6)
'junior doctor' is the definition.
(term for a student doctor)
'bury and wigan at last' is the wordplay.
'bury' becomes 'inter' (synonyms).
'and' is a charade indicator (letters next to each other).
'at last' indicates one should take the final letters.
The last letter of 'wigan' is 'n'.
'for' is the link.
(Other definitions for intern that I've seen before include "cage", "(American) hospital doctor", "Often unpaid trainee", "Hold in custody", "Shut up".)