Coolness of river with compacted snow around (5)
I believe the answer is:
nerve
'coolness' is the definition.
(thesaurus)
'river with compacted snow around' is the wordplay.
'river with' becomes 'r' (I can't justify this - if you can you should believe this answer much more).
'compacted snow' becomes 'neve' (nv is a type of snow).
'around' is an insertion indicator.
'r' placed inside 'neve' is 'NERVE'.
'of' is the link.
(Other definitions for nerve that I've seen before include "Boldness" , "Courage - cheek" , "Strand of body fibre" , "Grit" , "Valour, pluck" .)