Hal's upset about Vi being extravagant (6)
I believe the answer is:
lavish
'extravagant' is the definition.
(synonyms)
'hal's upset about vi' is the wordplay.
'upset' indicates an anagram.
'about' is an insertion indicator.
'hals' is an anagram of 'lash'.
'lash' enclosing 'vi' is 'LAVISH'.
'being' is the link.
(Other definitions for lavish that I've seen before include "Heap (money)" , "Abundant, generous" , "Extremely generous" , "Sumptuous" , "Plentiful or munificent" .)