The most common and most likely answer to this crossword clue is the 11 letter word CHAIRPERSON
I've seen this crossword clue in The Daily Telegraph
C
H
A
I
R
P
E
R
S
O
N
More clues leading to the result CHAIRPERSON
Buddy explains!
The straight part
We know that "who is in charge of assembly" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case who is in charge of assembly = chairperson.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 CHAIRPERSON mean?
CHAIRPERSON noun- A chairman or chairwoman, someone who presides over a meeting, board, etc.