Fold last of pages in dictionary inside comic (5,4)
I believe the answer is:
close down
'fold' is the definition.
(synonyms)
'last of pages in dictionary inside comic' is the wordplay.
'last of' suggests the final letters.
'in' means one lot of letters goes inside another.
'dictionary' becomes 'OED' (Oxford English Dictionary).
'inside' is an insertion indicator.
'comic' becomes 'clown' (clown is a kind of comic).
The final letter of 'pages' is 's'.
's' inserted inside 'oed' is 'osed'.
'osed' going into 'clown' is 'CLOSE-DOWN'.
(Other definitions for close down that I've seen before include "stop business" , "Shut completely, cease working" , "shut permanently" , "Cease trading" , "end of it" .)