Pick of elkhounds originally in pack (5)
I believe the answer is:
cream
'pick' is the definition.
(synonyms)
'elkhounds originally in pack' is the wordplay.
'originally' indicates taking the first letters.
'in' is an insertion indicator.
'pack' becomes 'cram' (synonyms).
The initial letter of 'elkhounds' is 'e'.
'e' placed into 'cram' is 'CREAM'.
'of' is the link.
(Other definitions for cream that I've seen before include "Thick milk" , "Dairy product" , "An off-white shade" , "The best part -of the crop" , "Elite; off-white" .)