The most common and most likely answer to this crossword clue is the 6 letter word WATSON
I've seen this crossword clue in The Daily Telegraph
W
A
T
S
O
N
More clues leading to the result WATSON
- Current events sidelining hospital doctor who recorded investigations
- Doctor was not bad
- Listings omitting Hotel Emily, for one
- Nobel laureate made TV appearance – about time!
- Doctor present upset nurses when taking temperature
- Crossworder’s focus not as fixed with “Solver’s Assistant”
- Doctor‘s inquiry about viewing hospital is ignored
- Doctor who documented his partner’s cases
- Doctor involved in many cases erasing hospital from schedule?
- Hold on — one leaving child with one’s roommate
Buddy explains!

The straight part
We know that "Doctor" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case doctor = watson.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.