The most common and most likely answer to this crossword clue is the 11 letter word TERRITORIES
I've seen this crossword clue in The Daily Telegraph
T
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Buddy explains!
The straight part
We know that "spheres of operation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case spheres of operation = territories.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 TERRITORIES mean?
TERRITORIES noun- A large extent or tract of land; for example a region, country or district.
- One of three of Canada's federated entities, located in the country's Arctic, with fewer powers than a province and created by an act of Parliament rather than by the Constitution: Yukon, Northwest Territories, and Nunavut.
- One of three of Australia's federated entities, located in the country's north and southeast, with fewer powers than a state and created by an act of Parliament rather than by the Constitution: Northern Territory, Australian Capital Territory and Jervis Bay Territory.
- A geographic area under control of a single governing entity such as state or municipality; an area whose borders are determined by the scope of political power rather than solely by natural features such as rivers and ridges.
- An area that an animal of a particular species consistently defends against its conspecifics.
- The part of the playing field or board over which a player or team has control.
- A geographic area that a person or organization is responsible for in the course of work.
- A location or logical space which someone owns or controls.
- A market segment or scope of professional practice over which an organization or type of practitioner has exclusive rights.
- An area of subject matter, knowledge, or experience.