Ray eager to straighten out something ill-defined (4,4)
I believe the answer is:
grey area
'something ill-defined' is the definition.
(a grey area is something vague or ill-defined)
'ray eager to straighten out' is the wordplay.
'to straighten out' indicates anagramming the letters.
'ray'+'eager'='rayeager'
'rayeager' is an anagram of 'GREY AREA'.
(Other definitions for grey area that I've seen before include "Ill-defined category" , "for which responsibility is unclear" , "subject to debate?" , "concrete jungle?" , "Unclear state of affairs" .)