The most common and most likely answer to this crossword clue is the 7 letter word ORPHANS
I've seen this crossword clue in The Guardian
O
R
P
H
A
N
S
Buddy explains!
The straight part
We know that "Waifs" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case waifs = orphans.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 ORPHANS mean?
ORPHANS noun- A person, especially a minor, both or (rarely) one of whose parents have died.
- A person, especially a minor, whose parents have permanently abandoned them.
- A young animal with no mother.
- Anything that is unsupported, as by its source, provider or caretaker, by reason of the supporter's demise or decision to abandon.
- A single line of type, beginning a paragraph, at the bottom of a column or page.
- Any unreferenced object.
- To deprive of parents (used almost exclusively in the passive)
- To make unavailable, as by removing the last remaining pointer or reference to.