The most common and most likely answer to this crossword clue is the 10 letter word SYNTHESISE
I've seen this crossword clue in The Daily Telegraph
S
Y
N
T
H
E
S
I
S
E
More clues leading to the result SYNTHESISE
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.
Crossword Answer definitions
SYNTHESISE verb- To combine two or more things to produce a new product.
- (of two or more things) To be combined producing a new, more complex product.
- To produce a substance by chemical synthesis.
- (of a substance) To be produced by chemical synthesis.