First-class to dine with drink included (4-2)
I believe the answer is:
slap-up
'first-class' is the definition.
(eg a slap-up meal, an excellent meal)
'dine with drink included' is the wordplay.
'dine with' becomes 'sup' (synonyms. I am not sure about the 'with' bit.).
'drink' becomes 'lap' (to lap is to drink up).
'included' means one lot of letters goes inside another.
'sup' enclosing 'lap' is 'SLAP-UP'.
'to' is the link.
Can you help me to learn more?
(Other definitions for slap-up that I've seen before include "Of meal, rich and plentiful" , "Very good, meal say" , "Lavish, meal say" , "This meal is first-class" , "Lavish (colloq.)" .)