Late, the disorganised sportsperson (7)
I believe the answer is:
athlete
'sportsperson' is the definition.
(I've seen this before)
'late the disorganised' is the wordplay.
'disorganised' indicates anagramming the letters.
'late'+'the'='latethe'
'latethe' with letters rearranged gives 'ATHLETE'.
(Other definitions for athlete that I've seen before include "Track/field sportsman" , "Contestant" , "Runner, jumper, thrower" , "gymnast, maybe" , "the hare that lost, say" .)