Escape from party with top-class athlete (2,1,6)
I believe the answer is:
do a runner
'escape' is the definition.
'party with top-class athlete' is the wordplay.
'party' becomes 'do' (do is a kind of party).
'with' means one lot of letters go next to another.
'top class' becomes 'a' (top grade).
'athlete' becomes 'runner' (runner is a kind of athlete**).
'do'+'a'+'runner'='DO A RUNNER'
'from' is the link.
(Other definitions for do a runner that I've seen before include "In slang, leave hastily - on the trot?" , "Scarper (without paying?)" , "beat it" , "Zambezi cataract" , "bolt" .)