The verb "duck" when used in the intransitive sense, means to dip or dive, or to duck the head. Its use in bridge implies the avoidance or evasion of or the deliberate attempt to lose a trick. It is very similar to
Declarer cashes a master card in a suit, thereby promoting an opponent's card to top rank. He then proceeds to execute a squeeze play and the opponent's apparent winner does not materialise.
