Watch for clues in Ravel medley (12)
I believe the answer is:
surveillance
'watch' is the definition.
(surveillance is keeping watch)
'clues in ravel medley' is the wordplay.
'medley' indicates an anagram.
'clues'+'in'+'ravel'='cluesinravel'
'cluesinravel' with letters rearranged gives 'SURVEILLANCE'.
'for' is the link.
(Other definitions for surveillance that I've seen before include "Close observation" , "Covert observation" , "Watch" .)