Mole has snack on river (4)
I believe the answer is:
pier
'mole' is the definition.
(thesaurus)
'snack on river' is the wordplay.
'snack' becomes 'pie'.
'on' says to put letters next to each other.
'river' becomes 'r'.
'pie'+'r'='PIER'
'has' acts as a link.
(Other definitions for pier that I've seen before include "Structure with a deck, built over water" , "Seaside structure" , "Seaside platform" , "Building projecting into the sea" , "Wharf jutting out into water" .)