Too nervous to go flat out? (5)
I believe the answer is:
jumpy
'too nervous' is the definition.
'jumpy' can be an answer for 'nervous' (synonyms). I am unsure of the 'too' bit.
'go flat out?' is the wordplay.
'go' becomes 'jump' (jumping is a kind of going).
'flat out?' becomes 'y' (I can't justify this - if you can you should give a lot more credence to this answer).
'jump'+'y'='JUMPY'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for jumpy that I've seen before include "Jittery" , "On edge" , "Anxious, uneasy" , "Nervous (as beans or fleas?)" .)