Small detached territory oddly insolvent (5)
I believe the answer is:
islet
'small detached territory' is the definition.
(a small island, so detached from land)
'oddly insolvent' is the wordplay.
'oddly' indicates alternate letters (letters in the odd-numbered positions are used).
The alternate letters of 'insolvent' are 'ISLET'.
(Other definitions for islet that I've seen before include "Very small area surrounded by water" , "Stile (anag)" , "named after Langerhans?" , "Tiles (anag.)" , "Rockall, for example" .)