Best man's bloomer omitting end of speech (8)
I believe the answer is:
champion
'best' is the definition.
(similar in meaning)
'man's bloomer omitting end of speech' is the wordplay.
I cannot really understand how this works, but
'of' could be 'o' and 'o' is found within the answer.
'man' could be 'ham' and 'ham' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for champion that I've seen before include "Champ" , "gain position on top" , "Person who has defeated all others in a competition" , "Competitor who has defeated all others" , "Winner of competition or supporter of cause" .)