The most common and most likely answer to this crossword clue is the 4 letter word WITH
I've seen this crossword clue in Financial Times
W
I
T
H
More clues leading to the result WITH
- In spite of horse, humorist gets up on it
- Characterised by humour bordering on humility
- Trendy comedian stricken
- In the company of comedian heading for hall
- See 21A
- Eagerly accompanied by Frank, member wanting ‘seconds’
- By law, it has limits
- Using wife, husband after sex
- Possessing ingenuity, lead in Hamlet
- Reason husband gets by
Buddy explains!

The straight part
We know that "In the company of" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in the company of = with.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 WITH mean?
WITH adverb- Along, together with others, in a group, etc.
- Against.
- In the company of; alongside, close to; near to.
- In addition to; as an accessory to.
- Used to indicate simultaneous happening, or immediate succession or consequence.
- In support of.
- In regard to.
- To denote the accomplishment of cause, means, instrument, etc; – sometimes equivalent to by.
- Using as an instrument; by means of.
- Using as nourishment; more recently replaced by on.
- Having, owning.
- Affected by (a certain emotion or condition).
- Prompted by (a certain emotion).
- A flexible, slender twig or shoot, especially when used as a band or for binding; a withy.
- A band of twisted twigs.
- An elastic handle to a tool to save the hand from the shock of blows.
- An iron attachment on one end of a mast or boom, with a ring, through which another mast or boom is rigged out and secured.
- A partition between flues in a chimney.