Appeared to accept a troubled raider's friendship (11)
I believe the answer is:
camaraderie
'friendship' is the definition.
(I've seen this before)
'appeared to accept a troubled raider's' is the wordplay.
'appeared' becomes 'came' (I've seen this before).
'to accept' means one lot of letters goes inside another.
'troubled' is an anagram indicator.
'raider' anagrammed gives 'raderi'.
'a'+'raderi'='araderi'
'came' enclosing 'araderi' is 'CAMARADERIE'.
(Other definitions for camaraderie that I've seen before include "Friendly sociability" , "Comradeship" , "Esprit de corps" , "all that backslapping?" , "Mutual trust and friendship" .)