Answer: moistener

AnswerCrossword Clue
MOISTENERStamp affixing aid.
MOISTENERWet sponge, for one.
MOISTENERUseful desk gadget.
MOISTENERWetting device for stamps
MOISTENERMailroom device
MOISTENERWet sponge
MOISTENERWhat a wet sponge may be used as
MOISTENEREnvelope-sealing aid
moistenersomething that moistens