Wise men with key to a form of sorcery (5)
I believe the answer is:
magic
'form of sorcery' is the definition.
'magic' can be an answer for 'sorcery' (I've seen this in another clue). I am not certain of the 'form of' bit.
'wise men with key' is the wordplay.
'wise men' becomes 'magi' (the three wise men from the nativity).
'with' means one lot of letters go next to another.
'key' becomes 'c' (musical key).
'magi'+'c'='MAGIC'
'to a' acts as a link.
Can you help me to learn more?
(Other definitions for magic that I've seen before include "Mysterious quality" , "Conjuror's art" , "Enchantment" , "Prestidigitation" , "Illusory feat" .)