Short acting lesson made shorter (4)
I believe the answer is:
dram
'lesson made shorter' is the definition.
I can't judge whether this definition defines the answer.
'short acting' is the wordplay.
'short' means to remove the last letter.
'acting' becomes 'drama' (I've seen this before).
'drama' with its final letter taken away is 'DRAM'.
Can you help me to learn more?
(Other definitions for dram that I've seen before include "Small drink of whisky" , "shot" , "Small drink (in Scotland)" , "Measure of Scotch" , "Tot of whisky" .)