crevice; crack; spare moment; interval; chink (in one's armor, armour); unpreparedness
chink in the armor (armour)
chink in the armor (armour)
one must constantly be on one's guard with ...; one cannot be too careful of ...
not busy; unengaged; being free; leisure
before one could; in no time at all; without a gap
gap; opening; crevice; crack