What a cowboy needs from girl with nothing (5)
I believe the answer is:
lasso
'what a cowboy needs' is the definition.
(a cowboy might use a lasso)
'girl with nothing' is the wordplay.
'girl' becomes 'lass' (lass can informally mean a girl).
'with' says to put letters next to each other.
'nothing' becomes 'o' (looks like zero - 0).
'lass'+'o'='LASSO'
'from' is the link.
(Other definitions for lasso that I've seen before include "Cowboy's noosed rope" , "Cow-catching rope?" , "Belgian composer" , "Rope for catching livestock" , "Looped rope used to catch cattle" .)