Crossword clue: marked by excessive enthusiasm for and intense devotion to a cause or idea
4 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).
Possible answers
a person motivated by irrational enthusiasm (as for a cause)
marked by excessive enthusiasm for and intense devotion to a cause or idea
marked by excessive enthusiasm for and intense devotion to a cause or idea
marked by excessive enthusiasm for and intense devotion to a cause or idea