Dumb little mammals consuming cool shrew's head (9)
I believe the answer is:
voiceless
'dumb' is the definition.
(I've seen this before)
'little mammals consuming cool shrew's head' is the wordplay.
'little mammals' becomes 'voles' (voles are small mammals).
'consuming' means one lot of letters goes inside another.
'cool' becomes 'ice' (icing is a kind of cooling).
'head' suggests taking the first letters.
The initial letter of 'shrews' is 's'.
'voles' going around 'ice' is 'voiceles'.
'voiceles'+'s'='VOICELESS'
(Other definitions for voiceless that I've seen before include "Mum" , "Dumb" .)