fox
kitsune
JMdict 1267340
きつねfoxはずるいcunning
Foxes are cunning
は (topic) raises 狐(きつね) (fox) as the topic — “as for the fox…”. The i-adjective ずるい (cunning) ends the sentence on its own, with no copula needed: in plain speech an i-adjective is already a complete predicate, so no だ (is) is added.