Lothario having Spanish wine with a son relaxing inside (8)
I believe the answer is:
casanova
'lothario' is the definition.
(thesaurus)
'spanish wine with a son relaxing inside' is the wordplay.
'spanish wine' becomes 'cava' (I've seen this before).
'with' means one lot of letters goes inside another.
'relaxing' indicates an anagram.
'inside' is an insertion indicator.
'son' is an anagram of 'sno'.
'a' going inside 'sno' is 'sano'.
'cava' enclosing 'sano' is 'CASANOVA'.
'having' is the link.
(Other definitions for casanova that I've seen before include "Amorous person" , "18th century Italian lover" , "Legendary lover" , "An Italian Don Juan" , "Italian adventurer, wrote vivid accounts of his amorous encounters" .)