Small mammal is almost cunning (5)
I believe the answer is:
shrew
'small mammal' is the definition.
'shrew' can be an answer for 'mammal' (shrew is a kind of mammal). I am not certain of the 'small' bit.
'almost cunning' is the wordplay.
'almost' means to remove the last letter (almost the whole word is kept).
'cunning' becomes 'shrewd' (I've seen this in another clue).
'shrewd' with its final letter removed is 'SHREW'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for shrew that I've seen before include "Harridan" , "Petruchio tamed one" , "eg Katharina" , "difficult woman" , "Mouse-like animal or scolding woman" .)