Sort of figure one must reform rough girl (9)
I believe the answer is:
hourglass
'sort of figure' is the definition.
(as in an hourglass figure)
'one must reform rough girl' is the wordplay.
'one must reform' is an anagram indicator (you must reform the letters).
'girl' becomes 'lass' (lass can informally mean a girl).
'rough' is an anagram of 'hourg'.
'hourg'+'lass'='HOURGLASS'
(Other definitions for hourglass that I've seen before include "classic figure" , "Old device for telling the time" , "Well-proportioned, with a small waist" , "Sand timer" , "it shows time's running out" .)