Associated Press write papers about Times supplement (8)
I believe the answer is:
appendix
'supplement' is the definition.
(I know that appendix is a type of supplement)
'associated press write papers about times' is the wordplay.
'associated press' becomes 'AP'.
'write' becomes 'pen' (synonyms).
'papers' becomes 'ID' (identification papers).
'about' is a reversal indicator.
'times' becomes 'x' (multiplication sign).
'id' reversed gives 'di'.
'ap'+'pen'+'di'+'x'='APPENDIX'
(Other definitions for appendix that I've seen before include "Extra section" , "Writer's addition - may be taken out in the theatre!" , "Reading matter" , "Addition to a book" , "Useless vestigial abdominal pouch" .)