Pop diva has drink, drinking case of Drambuie (5)
I believe the answer is:
adele
'pop diva' is the definition.
(Adele is a pop star)
'drink drinking case of drambuie' is the wordplay.
'drink' becomes 'ale' (type of beer).
'drinking' is an insertion indicator (inserted letters are consumed or drunk).
'case of' says to hollow out the word (remove centre letters) (outsides of).
'drambuie' with its middle taken out is 'de'.
'ale' placed around 'de' is 'ADELE'.
'has' is the link.
(Other definitions for adele that I've seen before include "Woman" , "Singer with albums titled 19, 21 and 25" , "Female singer from London" , "girl" , "Performer" .)