The girl is in dreadful need... (6)
I believe the answer is:
denise
'the girl' is the definition.
(Denise is a girl's name)
'is in dreadful need' is the wordplay.
'in' means one lot of letters goes inside another.
'dreadful' indicates an anagram.
'need' with letters rearranged gives 'dene'.
'is' going into 'dene' is 'DENISE'.
(Other definitions for denise that I've seen before include "- - Lewis, pentathlete" , "Miss Van Outen" .)