The most common and most likely answer to this crossword clue is the 6 letter word FRIEND
I've seen this crossword clue in The Guardian
F
R
I
E
N
D
More clues leading to the result FRIEND
- Devil embraces Remainers' leader, being intimate
- Demon securing King’s mate
- Female diner excited partner
- Father and I with close companion
- There’s little right in devil becoming a chum
- Republican admitted to bad spirit in China
- Foul spirit infused with drop of Ribena or a Bud?
- Intimate goal on day five
- . Sponsor‘s right to stop Formula One dying
- Just before Saturday, get intimate
Buddy explains!

The straight part
We know that "Quaker" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case quaker = friend.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 FRIEND mean?
FRIEND noun- A person other than a family member, spouse or lover whose company one enjoys and towards whom one feels affection.
- An associate who provides assistance.
- A person with whom one is vaguely or indirectly acquainted.
- A person who backs or supports something.
- An object or idea that can be used for good.
- (used only in the vocative) Used as a form of address when warning someone.
- A function or class granted special access to the private and protected members of another class.
- A spring-loaded camming device.
- A lover; a boyfriend or girlfriend.
- A relative, a relation by blood or marriage.
- To act as a friend to, to befriend; to be friendly to, to help.
- To add (a person) to a list of friends on a social networking site; to officially designate (someone) as a friend.