Nervous editor's gone running outside (2,4)
I believe the answer is:
on edge
'nervous' is the definition.
(thesaurus)
'editor's gone running outside' is the wordplay.
'editor' becomes 'ed'.
'running' is an anagram indicator.
'outside' is an insertion indicator.
'gone' anagrammed gives 'onge'.
'ed' put inside 'onge' is 'ON EDGE'.
(Other definitions for on edge that I've seen before include "Tense and irritable, very nervous" , "Nervously excited" , "Fidgety, nervous" , "Nervous and tense - close to cliff?" , "Cliff-top walker may be" .)