It's clear I'd entered competition (7)
I believe the answer is:
evident
'it's clear' is the definition.
(synonyms)
'i'd entered competition' is the wordplay.
'entered' indicates putting letters inside.
'competition' becomes 'event' (sporting event).
'id' going within 'event' is 'EVIDENT'.
(Other definitions for evident that I've seen before include "Clear to see" , "Obvious, may be plainly seen" , "Plain to see" , "on display" , "Conspicuous" .)