University lab rat on loose in capital (4,5)
I believe the answer is:
ulan bator
'capital' is the definition.
(capital of Mongolia)
'university lab rat on loose' is the wordplay.
'university' becomes 'U' (abbreviation for university).
'loose' indicates an anagram (letters are loosened from their original positions).
'lab'+'rat'+'on'='labraton'
'labraton' with letters rearranged gives 'lanbator'.
'u'+'lanbator'='ULAN BATOR'
'in' is the link.
(Other definitions for ulan bator that I've seen before include "capital city" , "Mongolian capital" , "Mongolian city" , "eastern city" , "Mongol city" .)