Spring rainfall's covering sportsperson (10)
I believe the answer is:
showjumper
'sportsperson' is the definition.
(I've seen this before)
'spring rainfall's covering' is the wordplay.
'spring' becomes 'jump' (synonyms).
'rainfall' becomes 'shower' (shower is a kind of rainfall).
'covering' indicates putting letters inside.
'jump' placed inside 'shower' is 'SHOWJUMPER'.
(Other definitions for showjumper that I've seen before include "one tackling obstacles in due course" , "equestrian" , "Sportsman" , "horse" , "performer in event" .)