Catchphrase, Habit Of Saying
Noun
くちぐせ
「何々が旬の季節です」ってあのシェフの口癖だよね。
That chef’s catchphrase is, "Such and such is in season."
A mouth habit is something you say with your mouth a lot. It's a habit. It's your favorite phrase or catchphrase. Many people have the habit of saying the certain things over and over again, whether they want to or not.
The reading is the kun'yomi vocab reading of both kanji. 癖 is the reading you learned with the kanji. Watch out for the rendaku.