To dine out with a girl is heavenly (6)
I believe the answer is:
divine
'heavenly' is the definition.
('divine' can be similar in meaning to 'heavenly')
'to dine out with a girl' is the wordplay.
'to dine out' becomes 'vine' (I can't justify this - if you can you should believe this answer much more).
'with' says to put letters next to each other.
'a girl' becomes 'di'.
'vine' put after 'di' is 'DIVINE'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for divine that I've seen before include "Predict" , "Theologian" , "Sacred; excellent" , "Search for water with a rod" , "of a splendid nature" .)