Uncomplaining in defeat (13)
I believe the answer is:
philosophical
'uncomplaining in defeat' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for philosophical that I've seen before include "Uncomplaining in defeat" , "Calmly uncomplaining" , "Serene in the face of adversity" , "Calm and stoical in the face of setbacks" , "Stoical in defeat" .)