Bit of sweat (4)
I believe the answer is:
bead
'bit of sweat' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for bead that I've seen before include "Drop of liquid on a surface" , "Small drop of moisture" , "Bauble" , "A bit of the rosary" , "Part of a necklace" .)