I would suggest: 風 with reading ふう , one of its meanings is ”wind” and fuu sounds like the wind
戦い/ 戦う fight/to fight, tatakai sounds like people fighting
Do you have any?
EDIT: Just words you personally think sound like their concepts, not necessarily confirmed as such.
4 comments
I’ve always thought 写真 shashin could be the clinking of a camera taking a photo.
You’ll be disappointed to know that ふ was pronounced Pu in Old Japanese (7th-9th century).
Adapting Chinese loanwords into Japanese was no easy feat!
A sempai told me that うるさい（五月蠅い）resembles the annoying sound for them in itself (I personally perceive the insects in sommer differently, but feel it could work for like a mosquito or fly going around your ears or a generally buzzing background)
Does this fit your question?
轟く とどろく, which means “to roar”. Buut when i was writing my research paper, I’ve found out that there’s an unconfirmed connection of that word to onomatopoeia ドロドロ.
Also there’s possibility, that non onomatopoeic words actually derived from old, ancient onomatopoeias. It happens a lot in Russian.