Skinflint's collection hidden in odd-looking casket (10)
I believe the answer is:
cheapskate
'skinflint's' is the definition.
(cheapskate is a kind of skinflint)
'collection hidden in odd-looking casket' is the wordplay.
'collection' becomes 'heap' (heap is a kind of collection).
'hidden in' is an insertion indicator.
'odd looking' indicates an anagram.
'casket' with letters rearranged gives 'cskate'.
'heap' going into 'cskate' is 'CHEAPSKATE'.
(Other definitions for cheapskate that I've seen before include "One's tight" , "Miserly person" , "Ungenerous type" , "Mean person" , "Tightwad" .)