Mount part of creature's skin? (5)
I believe the answer is:
scale
I believe this clue is a double definition.
'mount' is the first definition.
(scaling is a kind of mounting)
'part of creature's skin?' is the second definition.
(Other definitions for scale that I've seen before include "Deposit formed in a kettle or on teeth" , "Ratio between size and representation, on map say" , "Climb; overlapping plate" , "range" , "Doh, ray, me" .)