College turned on music (6)
I believe the answer is:
techno
'music' is the definition.
(I've seen this before)
'college turned on' is the wordplay.
'college' becomes 'tech' (technical college).
'turned' says the letters should be written backwards.
'on' back-to-front is 'no'.
'tech'+'no'='TECHNO'
(Other definitions for techno that I've seen before include "Form of electronic dance music" , "musical style" , "Style of electronic dance music" , "Music produced" , "type of music" .)