Clever little rodent died (6)
I believe the answer is:
shrewd
'clever' is the definition.
(I've seen this in another clue)
'little rodent died' is the wordplay.
'little rodent' becomes 'shrew' (shrew is a type of rodent).
'died' becomes 'd' (abbreviation next to the year of someone's death).
'shrew'+'d'='SHREWD'
(Other definitions for shrewd that I've seen before include "Sharp-witted" , "Having good judgment" , "Clever, having sound judgement" , "... knowing" , "keen" .)