Competitor - showy fellow, rises about five (5)
I believe the answer is:
rival
'competitor' is the definition.
(I know that competitor can be written as rival)
'showy fellow rises about five' is the wordplay.
'showy fellow rises' becomes 'rial' (I can't explain this - if you can you should believe this answer much more).
'about' means one lot of letters goes inside another.
'five' becomes 'V' (Roman numeral).
'rial' enclosing 'v' is 'RIVAL'.
Can you help me to learn more?
(Other definitions for rival that I've seen before include "Be equal to in quality" , "Emulate" , "Close competitor" , "Adversary, antagonist" , "Adversary or foe" .)