The most common and most likely answer to this crossword clue is the 10 letter word CHANCELLOR
I've seen this crossword clue in The Guardian
C
H
A
N
C
E
L
L
O
R
More clues leading to the result CHANCELLOR
- Minister’s opportunity to turn round
- Opportunity to wind up German leader, perhaps
- Opportunity to turn up for finance minister
- Lucky rollover for 20?
- Fortune, pounds, gold – all go into his purse
- Angela’s opportunity to stagger back?
- Record returns by coincidence for the one at this number?
- Official’s opportunity to get register back
- One with the opportunity to turn round?
- Minister put instrument into new ranch
Buddy explains!

The straight part
We know that "the one at this number" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case the one at this number = chancellor.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 CHANCELLOR mean?
CHANCELLOR noun- A senior secretary or official with administrative or legal duties, sometimes in charge of some area of government such as finance or justice.
- The head of the government in some German-speaking countries.
- A senior record keeper of a cathedral; a senior legal officer for a bishop or diocese in charge of hearing cases involving ecclesiastical law.
- The head of a university, sometimes purely ceremonial.
- Short for Chancellor of the Exchequer.
- The foreman of a jury.
- The chief judge of a court of chancery (that is, one exercising equity jurisdiction).