Crossword clue: vibrating slightly and irregularly; as e.g. with fear or cold or like the leaves of an aspen in a breeze

The most common answer is shivering (9 letters).

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

Possible answers

shivering 9 letters wn-def

a sensation of cold that often marks the start of an infection and the development of a fever

trembling 9 letters wn-def

a shaky motion