Lamb perhaps satisfied penning fourth of essays (4)
I believe the answer is:
meat
'lamb perhaps' is the definition.
(I know that lamb is a type of Meat)
'satisfied penning fourth of essays' is the wordplay.
'satisfied' becomes 'met' (as in 'met the conditions of his contract').
'penning' is an insertion indicator.
'fourth of essays' becomes 'a' (4th letter of 'essays').
'met' going around 'a' is 'MEAT'.
(Other definitions for meat that I've seen before include "Food for carnivores" , "Eg, beef or pork" , "Animal flesh as food" , "Spam, ham, lamb etc" , "Flesh for eating" .)