Short joke or witty remark (8)
I believe this is a double definition.
'short joke' is the first definition.
(I've seen this before)
'witty remark' is the second definition.
(I've seen this before)
(Other definitions for one-liner that I've seen before include "Quick quip?" , "Witty remark consisting of a short sentence" , "Witty remark contained in a single sentence" , "Flat, smooth" , "Terse joke" .)
(Another definition for oneliner that I've seen is " Witty remark".)