His desire lacks passion! (3)
I believe the answer is:
des
'his' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'desire lacks passion' is the wordplay.
'lacks' suggests deleting specific letters.
'passion' becomes 'ire' (ire is passionate anger).
'desire' with 'ire' removed is 'DES'.
Can you help me to learn more?
(Other definitions for des that I've seen before include "- O'Connor, Br. singer" , "and 9 Across: Former 'Countdown' host" .)