"Impossible!"
'impossible' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for no-go that I've seen before include "Can't be done, not on" , "Hopeless (informal)" , "Area forbidden to certain groups, maybe police" , "Prohibited area" , "Impossible task for goon" .)
(Other definitions for its that I've seen before include "Belonging to something nonhuman" , "Another form of 'tis" , "Belonging to a particular thing" , "Neuter possessive pronoun" , "The thing's" .)