Vague details about oxygen cut off (8)
I believe the answer is:
isolated
'cut off' is the definition.
(thesaurus)
'vague details about oxygen' is the wordplay.
'vague' indicates anagramming the letters.
'about' indicates putting letters inside.
'oxygen' becomes 'o' (atomic symbol for oxygen).
'details' is an anagram of 'islated'.
'islated' enclosing 'o' is 'ISOLATED'.
(Other definitions for isolated that I've seen before include "Segregated" , "Cut off, remote" , "Alone, apart, detached" , "Quarantined, alone" , "Solitary" .)