Leap year makes us nervous (5)
I believe the answer is:
jumpy
'nervous' is the definition.
(synonyms)
'leap year' is the wordplay.
'leap' becomes 'jump' (synonyms).
'year' becomes 'y'.
'jump'+'y'='JUMPY'
'makes us' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for jumpy that I've seen before include "Anxious, uneasy" , "Nervous (as beans or fleas?)" , "On edge" , "Jittery" .)