Attempted to justify; got fed up and finished (8)
I believe the answer is:
defended
'attempted to justify' is the definition.
I can't judge whether this definition defines the answer.
'fed up and finished' is the wordplay.
'up' is a reversal indicator (in down clue: letters go upwards).
'and' says to put letters next to each other.
'finished' becomes 'ended' ('end' can be a synonym of 'finish').
'fed' backwards is 'def'.
'def'+'ended'='DEFENDED'
'got' acts as a link.
Can you help me to learn more?
(Other definitions for defended that I've seen before include "Tried to justify" , "Guarded" , "Protected or supported against attack" , "Represented the accused in a lawsuit" , "Protected from harm" .)