Anxious energy to get on rides, at first (5)
I believe the answer is:
eager
'anxious' is the definition.
(eg being anxious to begin something)
'energy to get on rides at first' is the wordplay.
'energy' becomes 'eage' (I can't explain this - if you can you should give a lot more credence to this answer).
'to get on' is a charade indicator (letters next to each other) (in a down clue, some letters go above others).
'at first' indicates taking the first letters.
The first letter of 'rides' is 'r'.
'eage'+'r'='EAGER'
Can you help me to learn more?
(Other definitions for eager that I've seen before include "hungry" , "Desperate" , "Low platform" , "Swiss mountain" , "Impatient" .)