Look, needing engineers to replace a poor devil (6)
I believe the answer is:
wretch
'a poor devil' is the definition.
(I know that poor devil can be written as wretch)
'look needing engineers to replace' is the wordplay.
I cannot quite see how this works, but
'engineers' could be 're' (abbreviation for Royal Engineers) and 're' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for wretch that I've seen before include "Scoundrel" , "Despicable person" , "Miserable fellow" , "Someone to be pitied" , "Person in pitiful circumstances" .)