Single bars over river used by comedians (3,6)
I believe the answer is:
one-liners
'by comedians' is the definition.
Although both the answer and definition are plural nouns, I can't understand how they can define each other.
'single bars over river' is the wordplay.
'single' becomes 'one' (I've seen this before).
'bars' becomes 'lines' (I can't explain this - if you can you should believe this answer much more).
'over' means one lot of letters goes inside another.
'river' becomes 'r'.
'lines' going around 'r' is 'liners'.
'one'+'liners'='ONE-LINERS'
'used' is the link.
Can you help me to learn more?
(Other definitions for one-liners that I've seen before include "Quips" , "Short gags" .)