Feeble line put out from mischievous character (3)
I believe the answer is:
imp
'mischievous character' is the definition.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for imp that I've seen before include "little chap" , "Small devil or sprite" , "Rascal" , "Sprite; add feathers to" , "one likely to cause trouble" .)