The most common and most likely answer to this crossword clue is the 7 letter word STEPSON
I've seen this crossword clue in The Times
S
T
E
P
S
O
N
More clues leading to the result STEPSON
- Way informer turned up, trapping quiet family member
- Crushes a relative
- Walks over younger member of family
- Child recalled no small animals
- Member of extended family keeps walking
- Subdues male relative
- Relative stages revolutionary eastern drama
- Family member spent so recklessly
- Suppresses minor feature of new relationship?
- Dance-pop band playing for new partner’s child
Buddy explains!

The straight part
We know that "family member" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case family member = stepson.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 STEPSON mean?
STEPSON noun- The son of one's spouse, but not one's own child.