The most common and most likely answer to this crossword clue is the 7 letter word FOCUSED
I've seen this crossword clue in The Times
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More clues leading to the result FOCUSED
Buddy explains!

The straight part
We know that "single-minded" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case single-minded = focused.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 FOCUSED mean?
FOCUSED verb- (followed by on or upon) To concentrate one's attention.
- To cause (rays of light, etc) to converge at a single point.
- To adjust (a lens, an optical instrument) in order to position an image with respect to the focal plane.
- To concentrate one’s attention.
- To transfer the input focus to (a visual element), so that it receives subsequent input.
- Directing all one's efforts towards achieving a particular goal.
- Dealing with some narrowly defined aspects of a broader phenomenon.