(transitive, informal) to grab / (transitive, informal) to catch / (transitive, informal) to take / (intransitive, colloquial) to take root (of a plant) [auxiliary avere] / (intransitive, colloquial) to set (of varnish, stucco, etc.) [auxiliary avere]

(idiomatic) to be unable to find possible inroads or solutions to a problem; to be at a loss for what to do