Label for person who perseveres (7)
I believe the answer is:
sticker
I believe this clue is a double definition.
'label' is the first definition.
(I've seen this before)
'person who perseveres' is the second definition.
'for' is the link.
(Other definitions for sticker that I've seen before include "he soldiers on!" , "problem" , "Person with staying power" , "Gummed label" , "Adhesive label" .)