The most common and most likely answer to this crossword clue is the 10 letter word AMALGAMATE
I've seen this crossword clue in The Daily Telegraph
A
M
A
L
G
A
M
A
T
E
More clues leading to the result AMALGAMATE
- Mix in a Spanish city, having abandoned a friend
- Combine, in the morning, seaweed and chum
- Unite in the morning before gala arranged by friend
- A kind of rock climbing gets a working team to come together
- Compound in Malaga demolished by friend
- Combine to form new team after Alma’s replaced by Georgia
- Join a friend touring holiday destination, ignoring one area
- Combine fixing a game with Malta
- Join in the morning with buddy collecting seaweed
- A Spanish club dropping a fellow to consolidate
Buddy explains!

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 AMALGAMATE mean?
AMALGAMATE verb- To merge, to combine, to blend, to join.
- To make an alloy of a metal and mercury.
- To combine (free groups) by identifying respective isomorphic subgroups.
- Coalesced; united; combined.