The most common and most likely answer to this crossword clue is the 6 letter word UNITES
U
N
I
T
E
S
More clues leading to the result UNITES
- Couples decided wearing uniform is retrograde
- Joins educational institution before setback
- Joins Victorian 10s touring province
- Couples coming from Dorset in urge to head west
- Joins together tunes I composed
- Gets married, gets divorced, essentially having to cut back
- Distinguished men on board listened to allies
- Joins Confederates
- 22 Bands playing tunes about India
- Company's hiding electronic links
Buddy explains!

The straight part
We know that "allies" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case allies = unites.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 UNITES mean?
UNITES verb- To bring together as one.
- To come together as one.