Person who stands up for full back? (8)
I believe the answer is:
defender
This clue might be a double definition.
'person who stands up for full' is the first definition.
'defender' can be an answer for 'person' (defender is a kind of person). I am unsure of the rest of the definition.
'back?' is the second definition.
(I've seen this before)
Can you help me to learn more?
(Other definitions for defender that I've seen before include "Goalkeeper" , "One who protects from danger or takes one's side" , "Protector" , "One who takes up the cause of another" , "One who protects others" .)