Devils beheading feeble people (4)
I believe the answer is:
imps
'devils' is the definition.
(I have seen 'Little devils' mean 'imps' so perhaps 'devils' could also mean 'imps')
'beheading feeble people' is the wordplay.
'beheading' means to remove the first letter.
'feeble' becomes 'limp' (I've seen this before).
'people' becomes 's' (I can't justify this - if you can you should believe this answer much more).
'limp' with its first letter removed is 'imp'.
'imp'+'s'='IMPS'
Can you help me to learn more?
(Other definitions for imps that I've seen before include "Naughty sprites" , "Children causing trouble" , "Little rascals" , "Small devils or mischievous children" , "naughty children" .)