Fruit that's round, as it happens (5)
I believe the answer is:
olive
'fruit' is the definition.
(I've seen this before)
'round as it happens' is the wordplay.
'round' becomes 'o' (round can mean a round object).
'as it happens' becomes 'live' (as in live broadcasting).
'o'+'live'='OLIVE'
'that's' acts as a link.
(Other definitions for olive that I've seen before include "Cocktail fruit" , "This branch is offered to show peace" , "Mediterranean fruit or greenish colour" , "Fruit; Popeye's girlfriend" , "Female" .)