Answer: waning

AnswerCrossword Clue
WANINGGoing down.
waningthe act of waning
waningfall gradually from power, prosperity, or influence
waningflow out ebb
waningto decrease in size, extent, or degree dwindle as
waningbecome less brilliant or powerful dim
waningdiminish in phase or intensity used chiefly of the moon, other satellites, and inferior planets
WANINGPetering out
WANINGLike some moons
WANINGOn the way out
WANINGOn the decline
WANINGGrowing faint.
WANINGDeclining
WANINGIn decline
WANINGDeclining in power
WANINGDecreasing in intensity
WANINGDiminishing
WANINGLike a last-quarter moon
WANINGApproaching the third quarter, say