Request certain to provide delight (8)
I believe the answer is:
pleasure
'delight' is the definition.
('pleasure' can be a synonym of 'delight')
'request certain' is the wordplay.
'request' becomes 'plea' (plea is a kind of request).
'certain' becomes 'sure' ('sure' can be a synonym of 'certain').
'plea'+'sure'='PLEASURE'
'to provide' is the link.
(Other definitions for pleasure that I've seen before include "amusement" , "Happy satisfaction" , "Enjoyment, happiness" , "Gratification of the senses" , "contentment" .)