The most common and most likely answer to this crossword clue is the 5 letter word OATHS
I've seen this crossword clue in The Daily Telegraph
O
A
T
H
S
More clues leading to the result OATHS
- Nothing put forward in musketeer’s pledges
- Obscenities, if said by some yobs they’d be of themselves!
- Pledges to serve cereal in hospital? On the contrary!
- Swearing’s a little loathsome
- Loyalty has frequently produced solemn promises
- Promises husband to tuck into cereal
- Curses pipes around start of Hogmanay
- Curses musketeer over being posted to front
- Expletives coming from yob, aitches dropped regularly
- Has to set out professions of loyalty
Buddy explains!

The straight part
We know that "Vows" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vows = oaths.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 OATHS mean?
OATHS noun- A solemn pledge or promise, appealing to a deity, a ruler, or another entity (not necessarily present) to attest to the truth of a statement or sincerity of one's desire to fulfill a contract or promise.
- A statement or promise which is strengthened (affirmed) by such a pledge.
- A light, irreverent or insulting appeal to a deity or other entity.
- A curse, a curse word.
- To pledge.