Let a night with her set in motion true love! (3,4,5)
I believe the answer is:
the real thing
'true love' is the definition.
The definition and answer can be both human attributes as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'let a night with her set in motion' is the wordplay.
'with' says to put letters next to each other.
'set in motion' indicates an anagram (letters made to move around).
'let'+'a'+'night'+'her'='letanighther'
'letanighther' anagrammed gives 'THE REAL THING'.
Can you help me to learn more?
(Other definitions for the real thing that I've seen before include "genuine" , "Not an imitation or a substitute" .)