Show wicked American Triumph's top speed (10)
I believe the answer is:
illustrate
'show' is the definition.
(I know that illustrate is a more specific form of the action show)
'wicked american triumph's top speed' is the wordplay.
'wicked' becomes 'i'll' (I've seen this before).
'american triumph's top' becomes 'ust' (I can't explain this - if you can you should believe this answer much more).
'speed' becomes 'rate' (both can mean pace).
'ill'+'ust'+'rate'='ILLUSTRATE'
Can you help me to learn more?
(Other definitions for illustrate that I've seen before include "Ornament" , "Explain with pictures" , "picture" , "Give as example" , "Provide with pictures" .)