Supplement programme with part of game nine (8)
I believe the answer is:
appendix
'supplement' is the definition.
(I've seen this before)
'programme with part of game nine' is the wordplay.
'programme' becomes 'app'.
'with' says to put letters next to each other.
'part of game' becomes 'end' (eg the endgame in chess).
'nine' becomes 'ix' (roman numeral).
'app'+'end'+'ix'='APPENDIX'
(Other definitions for appendix that I've seen before include "Supplement at the end of a book" , "Table of subsidiary matter - vestigial organ" , "Final part of work" , "Addendum - vestigial pouch in human intestines" , "Addition to a book" .)