Judge an animal to have a prehensile tail (4)
I believe the answer is:
rate
'judge' is the definition.
(I know that rate is a more specific form of judge)
'an animal to have a prehensile tail' is the wordplay.
'an animal' becomes 'rat' (rat is a kind of animal).
'to have' means one lot of letters go next to another.
'tail' says to take the final letters.
The last letter of 'prehensile' is 'e'.
'rat'+'e'='RATE'
(Other definitions for rate that I've seen before include "Reckon; scold" , "Charge per unit" , "Strongly criticise" , "Think highly of - price" , "Regard" .)