College cracked my clue (6)
I believe the answer is:
lyceum
'college' is the definition.
(I've seen this before)
'cracked my clue' is the wordplay.
'cracked' indicates an anagram.
'my'+'clue'='myclue'
'myclue' anagrammed gives 'LYCEUM'.
(Other definitions for lyceum that I've seen before include "Athenian garden where Aristotle taught" , "Lecture-hall" , "Garden in Athens where Aristotle taught" , "My clue (anag)" , "Aristotle's garden" .)