Gulping oxygen, tired out journalist (6)
I believe the answer is:
editor
'journalist' is the definition.
(thesaurus)
'gulping oxygen tired out' is the wordplay.
'gulping' indicates putting letters inside (I've seen this in other clues).
'oxygen' becomes 'o' (atomic symbol for oxygen).
'out' is an anagram indicator (out can mean wrong or inaccurate).
'tired' is an anagram of 'editr'.
'o' put within 'editr' is 'EDITOR'.
(Other definitions for editor that I've seen before include "Paper head" , "Reviser" , "Senior publisher" , "Newspaper or publication chief" , "One is responsible for publication" .)