Devise song about film (where stars may be seen) (10)
I believe the answer is:
planetaria
'where stars may be seen' is the definition.
(plural of planetarium)
'devise song about film' is the wordplay.
'devise' becomes 'plan' (synonyms).
'song' becomes 'aria' (aria is a kind of song).
'about' is a charade indicator (letters next to each other).
'film' becomes 'ET' (E.T. the Extra-Terrestrial).
'aria' put after 'et' is 'etaria'.
'plan'+'etaria'='PLANETARIA'
(Other definitions for planetaria that I've seen before include "views of the sky" , "Where people see Pluto" , "Astronomical exhibitions" .)