Is losing first hair? Editor's anxious (8)
I believe the answer is:
stressed
'anxious' is the definition.
(I've seen this before)
'is losing first hair? editor's' is the wordplay.
'losing first' means to remove the first letter.
'hair?' becomes 'tress' (tress is a kind of hair**).
'editor' becomes 'ed'.
'is' with its initial letter taken off is 's'.
's'+'tress'+'ed'='STRESSED'
(Other definitions for stressed that I've seen before include "Subjected to strain or emphasised." , "Strained or emphasised" , "Placed emphasis on" , "Emphasized or strained" , "Accented, underlined" .)