A car for James Bond's boss, note (5)
I believe the answer is:
minim
'note' is the definition.
(type of musical note)
'a car for james bond's boss' is the wordplay.
'a car' becomes 'mini' (Mini Cooper).
'for' says to put 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" .)