Lantern's opening by ten gets wet (4)
I believe the answer is:
damp
'wet' is the definition.
(I know that wet can be written as damp)
I don't understand the remainder of the clue.
(Other definitions for damp that I've seen before include "Moist air" , "Slightly moist" , "Somewhat moist" , "soggy" , "Moisture" .)