The most common and most likely answer to this crossword clue is the 6 letter word MUTUAL
I've seen this crossword clue in The Times
M
U
T
U
A
L
More clues leading to the result MUTUAL
- Fall back, displacing new line in reciprocal arrangement
- Common umlaut design
- Fall in the US not entirely reversed, fifty shared
- Given and returned, coming back in fall, autumn
- Like a sort of friend — that’s what the traditional building society is!
- Financial institution with millions ends with you upset, you needing a pound
- Common feature of fallwestwards
- The ultimatum Tim rejected had been composed by both
- Shared on line: season almost over
- Mostly praise corporation over being member-owned
Buddy explains!

The straight part
We know that "in reciprocal arrangement" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in reciprocal arrangement = mutual.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 MUTUAL mean?
MUTUAL noun- A mutual fund.
- A mutual organization.
- Either of a pair of people who follow each other's social media accounts.
- Having the same relationship, each to each other.
- Collective, done or held in common.
- Reciprocal.
- Possessed in common.
- (Relating to a company, insurance or financial institution) Owned by the members.