Romeo excellent in competition (4)
I believe the answer is:
race
'competition' is the definition.
(I know that race is a type of competition)
'romeo excellent' is the wordplay.
'romeo' becomes 'r' (phonetic alphabet: alpha, bravo, charlie etc.).
'excellent' becomes 'ace' (I've seen this before).
'r'+'ace'='RACE'
'in' acts as a link.
(Other definitions for race that I've seen before include "Stock" , "People - sprint - competition" , "Run quickly" , "Breed" , "People; dash" .)