Round of bloomers in sport? Certain to be eliminated (3)
I believe the answer is:
lei
'round of bloomers' is the definition.
(garland of flowers)
'sport? certain to be eliminated' is the wordplay.
'sport?' becomes 'leisure' (sport is a leisure activity).
'certain' becomes 'sure' (synonyms).
'to be eliminated' is a deletion indicator.
'leisure' with 'sure' taken away is 'LEI'.
'in' acts as a link.
(Other definitions for lei that I've seen before include "Floral necklace" , "Honolulu chain of flowers" , "Blooming string" , "Flowers worn round the neck" , "Hawaiian garland of flowers" .)