Tumble dryer? It's in Northern Ireland (5)
I believe the answer is:
derry
'it's in northern ireland' is the definition.
(Northern Irish city)
'tumble dryer?' is the wordplay.
'tumble' indicates an anagram.
'dryer' with letters rearranged gives 'DERRY'.
(Other definitions for derry that I've seen before include "'The London - - Air' (mus.)" , "Port" , "Ulster city" .)