The most common and most likely answer to this crossword clue is the 5 letter word NIECE
I've seen this crossword clue in The Times
N
I
E
C
E
More clues leading to the result NIECE
- Terribly nice English family member
- A German turning back to welcome city relative
- Pleasant hosting European relative
- Pleasant entertaining eastern relative
- Family member, German one, returning from Cologne after vacation
- Family member that is entering new church
- Inheritance finally claimed by particular relative
- Relative of Bonnie wanting half the case about Clyde
- City area in Northern Ireland originally enticing family member
- Uncle’s child, agreeable to embrace revenge, finally
Buddy explains!

The straight part
We know that "Uncle’s child" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case uncle’s child = niece.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 NIECE mean?
NIECE noun- A daughter of one’s sibling, brother-in-law, or sister-in-law; either the daughter of one's brother ("fraternal niece"), or of one's sister ("sororal niece").