Possible runner’s articles about obstruction at Wimbledon (7)
I believe the answer is:
athlete
'possible runner's' is the definition.
(runner is a type of athlete)
'articles about obstruction at wimbledon' is the wordplay.
'articles' becomes 'athe' (two examples of the part-of-speech: a+the).
'about' is an insertion indicator.
'obstruction at wimbledon' becomes 'let' (tennis term).
'athe' enclosing 'let' is 'ATHLETE'.
(Other definitions for athlete that I've seen before include "Sportsman in track or field events" , "One good at sports" , "gymnast, perhaps" , "Announces impending danger" , "Bolt perhaps" .)