The most common and most likely answer to this crossword clue is the 6 letter word TOMBOY
I've seen this crossword clue in Financial Times
T
O
M
B
O
Y
More clues leading to the result TOMBOY
- Feisty female to play Doctor Who, at last, enters
- , 19. Hooligan facing test, all about being female, not ladylike
- Romp with old doctor in play
- Feisty female Doctor Who at last seen in play
- Grave old year for Georgina Kirrin?
- Sort of girl that’s grave with zero yen
- Lout returns to support prostitute
- Boisterous girl’s play about old doctor
Buddy explains!

The straight part
We know that "Romp" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case romp = tomboy.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 TOMBOY mean?
TOMBOY noun- A girl who behaves in a typically boyish manner.
- A lesbian.