She's on the line (3)
I believe the answer is:
peg
'she's' is the definition.
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for peg that I've seen before include "that may have hat or coat on" , "Kind of clip for fastening clothes to line" , "The woman" , "Clip for attaching clothes to line" , "Wooden pin, small marker" .)