Discover king and queen finally (5)
I believe the answer is:
learn
'discover' is the definition.
(I know that discover can be written as learn)
'king and queen finally' is the wordplay.
'king' becomes 'lear' (Shakespeare's King Lear).
'and' means one lot of letters go next to another.
'finally' says to take the final letters.
The last letter of 'queen' is 'n'.
'lear'+'n'='LEARN'
(Other definitions for learn that I've seen before include "Come to know" , "Read up on" , "Become aware of" , "Acquire information" , "Study or digest" .)