Eg runner’s articles about obstruction in game (7)
I believe the answer is:
athlete
'eg runner's' is the definition.
(runner is a kind of athlete)
'articles about obstruction in game' is the wordplay.
'articles' becomes 'a the' ('a' and 'the', indefinite and definite articles).
'about' indicates putting letters inside.
'obstruction in game' becomes 'let' (tennis term).
'athe' going around 'let' is 'ATHLETE'.
(Other definitions for athlete that I've seen before include "Contestant" , "One who engages in physical sports" , "Track/field sportsman" , "expected to be agile, of course" , "Jumper, say" .)