Bad clue butchered by editor originally (can be trained) (8)
I believe the answer is:
educable
'can be trained' is the definition.
(able to be educated)
'bad clue butchered by editor originally' is the wordplay.
'butchered' is an anagram indicator (I've seen this in other clues).
'by' is a charade indicator (letters next to each other).
'originally' suggests taking the first letters.
The first letter of 'editor' is 'e'.
'bad'+'clue'='badclue'
'badclue' is an anagram of 'educabl'.
'educabl'+'e'='EDUCABLE'
(Other definitions for educable that I've seen before include "Able to be trained" , "as good students should be" , "Capable of being taught" , "can take in information" .)