Bowie ultimately thin in black (5)
I believe the answer is:
ebony
'black' is the definition.
(ebony is a kind of black)
'bowie ultimately thin' is the wordplay.
'ultimately' suggests the final letters.
'thin' becomes 'bony' (similar in meaning).
The last letter of 'bowie' is 'e'.
'e'+'bony'='EBONY'
'in' acts as a link.
(Other definitions for ebony that I've seen before include "Black hardwood" , "Dark hardwood" , "Tree having black wood" , "Very dark black" , "'Hard, dark wood (5)'" .)