Half of them came upon prince stabbed by knight? Hard cheese! (9)
I believe the answer is:
emmenthal
'cheese' is the definition.
(Emmenthal is an example)
'half of them came upon prince stabbed by knight? hard' is the wordplay.
'half of' means to take half the letters.
'came upon' becomes 'met' (I've seen this in another clue).
'prince' becomes 'hal' (Shakespearean nickname of Henry V when a prince).
'stabbed by' means one lot of letters goes inside another (some letters stab themselves into others).
'knight? hard' becomes 'n' (chess abbreviation. I am not sure about the 'hard' bit.).
'them' with half the letters taken is 'em'.
'met'+'hal'='methal'
'methal' going around 'n' is 'menthal'.
'em'+'menthal'='EMMENTHAL'
Can you help me to learn more?
(Other definitions for emmenthal that I've seen before include "Something cheesy" , "Type of cheese" , "Swiss cheese with holes" , "Hard Swiss cheese" , "Swiss valley giving its name to a cheese" .)