Generally, if a puzzle is put on hold as being "too broad," it is because there are too many potential answers that fit with the clues. You obviously have one specific answer in mind, but perhaps you have failed to sufficiently constrain the answer space so as to invalidate other potential answers.
One good way to avoid this problem is to include some clues that are plays on words or use a different meaning of the word.
For example, suppose I posted a riddle as follows:
Tall and wooden,
I move in the breeze
Flashing my colors
I stand there with ease
Now, my intended answer is a tree in the autumn, but an equally valid interpretation might be a flagpole and flag.
To narrow it down, I could add further hints (something about "branches", maybe), but I always run the risk of there being other things that still fit the description.
A better option is to use a play on words, which will only be relevant to my intended answer and is much more likely to invalidate any other answer, because it requires a specific word/words to make it work:
One certain type at the seashore is found (beach/beech)
Another type after a fire is drowned (ash)
With these added lines, the flagpole answer is completely invalidated, as is any other answer that shares only physical characteristics with the first stanza. It is now much more likely that any reasonable answer will at least come close to my intended answer.
What it comes down to is that crafting a good riddle is more than saying "guess what I'm thinking of!" It requires some careful crafting and perhaps "trickery" to narrow down prospective solutions.
When someone finds the answer, they should be saying, "Aha! That's obviously it! It fits all the clues like so...". They should not be saying, "I think this is it, because it mostly matches the clues...".