Surprisingly, she ran alongside Nazis, showing lack of judgement (8)
I believe the answer is:
rashness
'lack of judgement' is the definition.
'rashness' can be an answer for 'lack' (I have seen 'Lack of caution ' mean 'rashness' so perhaps 'lack' could also mean 'rashness'). I am not sure about the 'of judgement' bit.
'surprisingly she ran alongside nazis' is the wordplay.
'surprisingly' is an anagram indicator (a surprising ordering of the letters).
'alongside' says to put letters next to each other.
'nazis' becomes 'SS' (the SS was a Nazi organisation).
'she'+'ran'='sheran'
'sheran' with letters rearranged gives 'rashne'.
'rashne'+'ss'='RASHNESS'
'showing' acts as a link.
Can you help me to learn more?
(Other definitions for rashness that I've seen before include "Recklessness" , "intemperance" , "Impulsiveness" , "indiscretion" , "Impetuosity" .)