Rues dunce somehow becoming loose (9)
I believe the answer is:
unsecured
'loose' is the definition.
(thesaurus)
'rues dunce somehow' is the wordplay.
'somehow' indicates anagramming the letters.
'rues'+'dunce'='ruesdunce'
'ruesdunce' with letters rearranged gives 'UNSECURED'.
'becoming' acts as a link.
(Other definitions for unsecured that I've seen before include "Not locked" , "on the loose" , "liable to come off" .)