With 43-Across, playful marine mammal

SEA

Think of the first word in "ocean" to pair with 43-Across for a dolphin’s watery home.

This clue is part of a split answer where "SEA" combines with 43-Across to form "SEA LION," a well-known playful marine mammal. The wordplay here relies on the answer being incomplete until paired with its counterpart later in the grid. It’s a common crossword trick to split phrases when they’re too long for a single entry. Think of it like a puzzle piece—you’ll need both parts to see the full picture.