Hardy girl, least upset inside, getting vulgar (9)
I believe the answer is:
tasteless
'vulgar' is the definition.
('tasteless' can be similar in meaning to 'vulgar')
'hardy girl least upset inside' is the wordplay.
'hardy girl' becomes 'tess'.
'upset' indicates an anagram.
'inside' indicates putting letters inside.
'least' is an anagram of 'astel'.
'tess' going around 'astel' is 'TASTELESS'.
'getting' is the link.
(Other definitions for tasteless that I've seen before include "Lacking in aesthetic judgement" , "Unseemly" , "improper" , "Insipid - inappropriate - dull" , "Bland; offensive" .)