Request written with certain enjoyment (8)
I believe the answer is:
pleasure
'enjoyment' is the definition.
(I've seen this before)
'request written with certain' is the wordplay.
'request' becomes 'plea' (plea is a kind of request).
'written with' says to put letters next to each other.
'certain' becomes 'sure' (synonyms).
'plea'+'sure'='PLEASURE'
(Other definitions for pleasure that I've seen before include "A desirable emotion" , "contentment" , "amusement" , "Delight, happiness" , "Delight, joy" .)