"Zip it!" (7)
(Other definitions for race that I've seen before include "People - sprint - competition" , "put their skates on" , "Speed competition" , "Contest; nation" , "Running contest" .)
(Another definition for shush that I've seen is " Interjection for keep quiet, don't make noise".)
(Other definitions for silence that I've seen before include "may be required in court" , "Absence of racket" , "It is golden, they say" , "Quiet" , "Absence of sound" .)
(Other definitions for shh that I've seen before include "Be quiet!" , "Be silent" .)