Regex function to return string between 2 charactes

AbdulBalogun

Im trying to create a regex function that gives me the string between 2 characters

I have the string below 

word1/word2/word3/word4/word5/word6/word7/word8_length_string.txt

and I'm trying to return everything after the 7th instance of "_" and before ".txt"

is there a regex function within the regex tool I can use to accomplish this?

binu_acs

@AbdulBalogun another regex

Regex_08052024.yxmd