The most common and most likely answer to this crossword clue is the 7 plus 5 letter word PECKING ORDER
I've seen this crossword clue in Financial Times
P
E
C
K
I
N
G
O
R
D
E
R
More clues leading to the result PECKING ORDER
- Hierarchy strictly for the birds?
- Animal Farm hierarchy, where pig reckoned to be barbaric dictator, ultimately
- “Kiss me, quick!” — one’s relative standing in it
- Exercises on record oddly involving monarch and hierarchy
- Hierarchy of kissing brothers?
- ‘Kiss me quick’? That’s rank
- Instruction given by head of commerce in Beijing hierarchy
- Instruction to kiss in sequence of social status
- Measure of importance under the mistletoe?
- Kiss suitable to maintain good set of relationships
Buddy explains!
The straight part
We know that "set of relationships" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case set of relationships = pecking order.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.