If you are writing a poem with a line ending 'for sure', I would advise, so that you do not need to go off on a tangent and write gibberish, that you change your wording or word order. This may mean that you need to rewrite the whole line, however. Certainly is appreciably not a very poetic word (I certainly wouldn't use it), and neither is definitely. Therefore, you'd be better off moving the words around. If this is absolutely not possible and there are no synonyms for what you are trying to convey...
Combinations rhyming with 'for sure' (as I don't believe there are any single words that do) include 'more poor', 'poor law' and 'poor whore' (all of which I may include in my own poetry, so don't think I'm being an idiot). 'For' rhymes with 'sure', so there are many words that would fit, and they are interchangeable, but some make no sense, perhaps because they are both nouns or some similar explanation.
Of course, there is also the option of a half rhyme, whereby you find something that rhymes with 'sure' only. For this, there is a very large range, including words from the above text, but also 'shore' (not preferable as it is a homophone, in my opinion anyway) 'sore', 'claw', 'straw', 'paw'. There is a massive range, but only some will be even applicable. If your poem is about animals, it would be best to use something like 'paw', 'claw', 'saw' or 'shore' (for marine animals especially). If its perhaps a poem about love, 'more', 'saw' or 'pour' may be applicable. You get the picture, I hope.
Overall, I would advise that you first try to find different words to convey the story. To do this, you may even have to change other lines, but it is something I do. Then consider, if just rearranging fails, the different rhymes of your words, as above; bear in mind that not all words will actually work. Then, if none of my suggestions work, resort to a simple half-rhyme. If this fails, literally just erase that line, take a decent break and return.
I hope this helps you...
Some words that rhyme with "for sure" include implore, allure, and procure.
boy forsure
Tundra forsure!
rap, forsure
rap, forsure
In ancient athens, we are forsure about that.
You should forsure call him. You never know what could come out of it. No matter what happens though, not knowing is forsure worse than just hearing what he has to say. No. He is your ex.
Older than you thats forsure
i beleve they alredy did but if not they are forsure comming
I THOUGHT it was Priestess.. but I am not positive.. Does anyone know forsure?
Not forsure, But I think that it's the desert part of israel, the southern part.
I think Courageous is based on a true story but I'm not forsure.
1:12 forsure