Cake Blog reviewed jam (8)
I believe the answer is:
blockage
'jam' is the definition.
(I've seen this before)
'cake blog reviewed' is the wordplay.
'reviewed' is an anagram indicator (letters reviewed or revised).
'cake'+'blog'='cakeblog'
'cakeblog' is an anagram of 'BLOCKAGE'.
(Other definitions for blockage that I've seen before include "Obstruction" , "jam" , "Clot" .)