Nervous editor going crazy ultimately (4)
I believe the answer is:
edgy
'nervous' is the definition.
(synonyms)
'editor going crazy ultimately' is the wordplay.
'editor' becomes 'ed' (abbreviation).
'ultimately' indicates one should take the final letters.
The final letters of 'going crazy' are 'gy'.
'ed'+'gy'='EDGY'
(Other definitions for edgy that I've seen before include "Nervous and tense, irritable" , "Red shade" , "Uneasy" , "Extremely" , "Visibly nervous" .)