The most common and most likely answer to this crossword clue is the 10 letter word GUARANTIES
I've seen this crossword clue in The Guardian
G
U
A
R
A
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Buddy explains!
The straight part
We know that "undertakings to be responsible" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case undertakings to be responsible = guaranties.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 GUARANTIES mean?
GUARANTIES verb- To give an assurance that something will be done right.
- To assume or take responsibility for a debt or other obligation.
- To make something certain.
- An undertaking to answer for the payment of some debt, or the performance of some contract or duty, of another, in case of the failure of such other to pay or perform; a warranty; a security.
- Something serving as a security for such an undertaking.
- An assurance or guarantee.