Girl with nothing but a rope (5)
I believe the answer is:
lasso
'a rope' is the definition.
(I know that rope can be written as lasso)
'girl with nothing' is the wordplay.
'girl' becomes 'lass' (lass can informally mean a girl).
'with' means one lot of letters go next to another.
'nothing' becomes 'O' (looks like zero - 0).
'lass'+'o'='LASSO'
'but' acts as a link.
(Other definitions for lasso that I've seen before include "something to catch beast liable to run off" , "One may be caught by this" , "Somehow catch" , "Rope for throwing" , "Cow-catching rope?" .)