The most common and most likely answer to this crossword clue is the 8 letter word RIPARIAN
I've seen this crossword clue in The Times
R
I
P
A
R
I
A
N
More clues leading to the result RIPARIAN
- Final send-off for heretic connected with bank
- Single French capitalist losing heart after run on bank
- Referring to river bank rain pair recollected
- Farewell message to heretic in riverside area
- Pick up Irish porcelain associated with banks
- He owns land next to the bank
- Pair wandering around Iran having accident by river
- Rest peacefully by a river with Scot on the bank
- Scotsman to invest capital short after run on bank
Buddy explains!

The straight part
We know that "on the bank" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case on the bank = riparian.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does RIPARIAN mean?
RIPARIAN noun- A person or other entity that lives or owns property along the shore of a river.
- Of or relating to the bank of a river or stream.