Play in which King Lear goes mad and loses throne ultimately (4)
I believe the answer is:
lark
'play' is the definition.
(larking is a kind of playing)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for lark that I've seen before include "Flighty type" , "what one may get up to?" , "Jape; bird" , "Singing bird and piece of harmless mischief" , "Songbird - 3" .)