Small drop of moisture (4)
I believe the answer is:
bead
'small drop of moisture' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for bead that I've seen before include "Drop of liquid on a surface" , "Necklace piece; droplet" , "Small ball with a hole through the middle" , "Part of a necklace" , "Small round piece of glass" .)