Mars unusual three-D map accompanying film (3,3,6)
I believe the answer is:
the red planet
'mars' is the definition.
(I've seen this before)
'unusual three-d map accompanying film' is the wordplay.
'unusual' indicates an anagram.
'map' becomes 'plan' (I've seen this before**).
'accompanying' means one lot of letters go next to another.
'film' becomes 'et'.
'three' with letters rearranged gives 'there'.
'there'+'d'+'plan'+'et'='THE RED PLANET'
(Other definitions for the red planet that I've seen before include "Mars" , "out-of-this-world destination" , "One of our neighbours" .)