Uncomplaining person (5)
I believe the answer is:
stoic
'uncomplaining person' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for stoic that I've seen before include "Seeming unaffected by pleasure or pain" , "One who endures pain with equanimity" , "Resigned" , "One patient under misfortune" , "Phlegmatic type" .)