It may be deadlier off the tracks (8)
I believe the answer is:
derailed
'off the tracks' is the definition.
I can't judge whether this defines the answer.
'it may be deadlier' is the wordplay.
'it may be' indicates an anagram (I've seen this in other clues).
'deadlier' with letters rearranged gives 'DERAILED'.
Can you help me to learn more?
(Other definitions for derailed that I've seen before include "Forced off the tracks" , "To be off the track" .)