Sentence:  It was so cold and so wretched that a sort of desperate gaiety infected all of them , like people stormbound or shipwrecked or caught in some other freak of circumstance so that time stood still and minor anxieties fell away and the only important thing was to <WSD>cling</WSD> together and survive . 
Meaning of the word marked with <WSD> tags:  come or be in close contact with; stick or hold together and resist separation