The most common and most likely answer to this crossword clue is the 11 letter word MATCHMAKING
I've seen this crossword clue in The Sunday Telegraph
M
A
T
C
H
M
A
K
I
N
G
Buddy explains!
The straight part
We know that "forming a relationship" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case forming a relationship = matchmaking.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 MATCHMAKING mean?
MATCHMAKING verb- To do matchmaking: to set up a date between two people or to arrange a marriage.
- An attempt to make two people romantically interested in each other, especially an attempt to set up a date between people or to arrange a marriage.
- A service aiming to bring together sellers and buyers or potential partners.
- The act or process of locating suitable players to take part in a multiplayer game session.
- The manufacture of matches for kindling or burning.