Old man in retirement with little desire (8)
I believe the answer is:
appetite
'desire' is the definition.
(appetite is a kind of desire)
'old man in retirement with little' is the wordplay.
'old man' becomes 'pa' (both can mean someone's father).
'in retirement' shows that the letters should be reversed in order (retire can mean to go back or backwards).
'with' means one lot of letters go next to another.
'little' becomes 'petite' (similar in meaning).
'pa' in reverse letter order is 'ap'.
'ap'+'petite'='APPETITE'
(Other definitions for appetite that I've seen before include "Desire or liking, for power or food" , "Desire, relish" , "thirst" , "Physical need for food" , "enthusiasm" .)