A car for James Bond's boss, note (5)
I believe the answer is:
minim
'note' is the definition.
(musical note)
'a car for james bond's boss' is the wordplay.
'a car' becomes 'mini' (Mini Cooper).
'for' is a charade indicator (letters next to each other).
'james bond's boss' becomes 'm' (M is the head of MI6 in the James Bond series).
'mini'+'m'='MINIM'
(Other definitions for minim that I've seen before include "Note equal to two crochets" , "Half-note" , "Palindromic note" , "A note in music, half as long as a semi-breve- it's a palindrome" , "Note of two crotchets" .)