Bit of rain (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">bit of rain</span>' is the definition.<br/ ><span class="explanation-format__explanation">(a drop of rain is a bit of rain)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for drop that I've seen before include "Shoot" , "Small drink" , "Wee dram" , "Fall; abandon" , "Discontinue; sink" .)