Slander linked to apartment, riverside feature (7)
I believe the answer is:
mudflat
'riverside feature' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'slander linked to apartment' is the wordplay.
'slander' becomes 'mud' (as in to drag someone's name through the mud).
'linked to' says to put letters next to each other.
'apartment' becomes 'flat' (synonyms).
'mud'+'flat'='MUDFLAT'
Can you help me to learn more?
(Other definitions for mudflat that I've seen before include "area of seaside land" , "estuary area" .)