King Harry maybe appearing heartless — something you can find in Shakespeare (5)
I believe the answer is:
rhyme
'something you can find in shakespeare' is the definition.
I can't tell whether this defines the answer.
'king harry maybe appearing heartless' is the wordplay.
'king' becomes 'R' (abbreviation for rex, king in Latin).
'harry' becomes 'hy' (I am not sure about this - if you are sure you should believe this answer much more).
'appearing heartless' suggests removing the centre (the heart of the word is removed).
'maybe' with its middle removed is 'me'.
'r'+'hy'+'me'='RHYME'
Can you help me to learn more?
(Other definitions for rhyme that I've seen before include "Short poem" , "Box and cox, for example" , "Be like 'cat' and 'mat'" , "Sound correspondence" , "End with a similar sound" .)