Fussy and irritable, looking neither to right nor (later) left (5)
I believe the answer is:
picky
'fussy' is the definition.
(I know that fussy can be written as picky)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for picky that I've seen before include "Discriminating" , "Excessively fastidious" , "Choosy" , "Excessively particular" , "Finicky" .)