The most common and most likely answer to this crossword clue is the 2 letter word AT
A
T
Buddy explains!

The straight part
We know that "Working with" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case working with = at.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 AT mean?
AT verb- To reply to or talk to someone, either online or face-to-face. (from the practice of targeting a message or reply to someone online by writing @name)
- The at sign (@).
- In, near, or in the general vicinity of a particular place.
- (indicating time) Indicating occurrence in an instant of time or a period of time relatively short in context or from the speaker's perspective.
- In the direction of (often in an unfocused or uncaring manner).
- Denotes a price.
- Occupied in (activity).
- In a state of.
- Indicates a position on a scale or in a series.
- Because of.
- Indicates a means, method, or manner.
- Holding a given speed or rate.
- (used for skills (including in activities) or areas of knowledge) On the subject of; regarding.
- (stressed pronunciation) Bothering, irritating, causing discomfort to
- Reduced form of that.
- A subdivision of currency, equal to one hundredth of a Lao kip.