Prefix with "maid" for a mythical sea creature that's half-fish, half-human

On ___ with (at the same level)3 School fundraising group: Abbr.3 Appendage that may be rested on a recliner3 Below-the-ground plant part4 Bodybuilder's chest muscle, for short3 Meal at the park with friends, say6 Jazz legend Fitzgerald referred to as the "First Lady of Song"4 Bangs holder4