Ounce fraction (4)
I believe the answer is:
dram
'ounce fraction' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for dram that I've seen before include "Measure of spirits" , "shot" , "Wee drop of whisky?" , "Measure of Scotch" , "Pick-me-up" .)