Anxious knight, very agitated (5)
I believe the answer is:
nervy
'anxious' is the definition.
(I've seen this before)
'knight very agitated' is the wordplay.
'knight' becomes 'n' (chess abbreviation).
'agitated' is an anagram indicator.
'very' is an anagram of 'ervy'.
'n'+'ervy'='NERVY'
(Other definitions for nervy that I've seen before include "Anxious, jumpy" , "Highly-strung" , "close to the edge?" , "Fidgety" , "Easily agitated, tense" .)