Complete cessation of punctuation (4,4)
I believe the answer is:
full stop
'punctuation' is the definition.
(full stop is a kind of punctuation)
'complete cessation' is the wordplay.
'complete' becomes 'full' (associated in meaning).
'cessation' becomes 'stop' (I've seen this in another clue).
'full'+'stop'='FULL-STOP'
'of' acts as a link.
(Other definitions for full stop that I've seen before include "finalised" , "A period in the US!" , "Point" , "'Punctuation mark (4,4)'" , "period in America" .)