Pen name of Charles Lamb (4)
I believe the answer is:
elia
'pen name of charles lamb' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for elia that I've seen before include "1A [SHEEPISH] part of 26 [LAMB-DA]" , "Charles Lamb's pen name" , "Pseudonym of Charles Lamb, 1775-1834" , "Essays of - (Charles Lamb)" , "Pseudonym adopted by Charles Lamb" .)