Nun dwelt in terribly draughty place (4,6)
I believe the answer is:
wind tunnel
'draughty place' is the definition.
(I've seen this before)
'nun dwelt in terribly' is the wordplay.
'terribly' indicates anagramming the letters.
'nun'+'dwelt'+'in'='nundweltin'
'nundweltin' is an anagram of 'WIND-TUNNEL'.
(Other definitions for wind tunnel that I've seen before include "Where to test in flow" , "Experimental aerodynamic chamber" , "Structure for testing aircraft parts by blowing air over them" , "Airflow simulator" , "Blasted trial here" .)