Romantic film -- overtly, so fanciful (4,5)
I believe the answer is:
love story
'romantic film' is the definition.
(1970 romantic film)
'overtly so fanciful' is the wordplay.
'fanciful' indicates an anagram (a fanciful or silly ordering of the letters).
'overtly'+'so'='overtlyso'
'overtlyso' is an anagram of 'LOVE-STORY'.
(Other definitions for love story that I've seen before include "Romantic tale" , "amorous relation" .)