Sent bitcoins to a suspicious address!
I think Opt-in Replace By Fee is what you are looking for. The wallets implementing RBF lets you mark your transactions as unfinished and that let's you replace it with more fees than the previous one. But merchants are advised to wait for at least one confirmation before accepting optin rbf transactions (to avoid a double spending risk).

The only wallet I know that have implemented RBF is Electrum.

Below you have some useful links:

https://bitcoincore.org/en/faq/optin_rbf/

https://petertodd.org/2016/are-wallets-ready-for-rbf

https://electrum.org/#home