Celebrity policemen are on to sailor (9)
I believe the answer is:
superstar
'celebrity' is the definition.
(I know that superstar is a type of star)
'policemen are on to sailor' is the wordplay.
'policemen are' becomes 'supers' (I can't explain this - if you can you should believe this answer much more).
'on' is a charade indicator (letters next to each other).
'to sailor' becomes 'tar' (slang term for a sailor).
'supers'+'tar'='SUPERSTAR'
Can you help me to learn more?
(Other definitions for superstar that I've seen before include "Dazzling virtuoso" , "Celeb" , "top celebrity" , "Very famous person" , "Dazzling genius" .)