I have a friend that's trying to join my clan but when he searches for it, my clan doesn't come up.
Best way to do this would be to give your friend your clan tag. (It's a 7 character alpha-numeric code preceded by a #).
Your friend can then enter that into the search box and find your clan.
I had the same problem; where i joined a clan with several pages worth of others with the same name. This worked perfectly for me.
When I created my first clan, I named it after my favorite show from my childhood: Naruto (a popular anime). However, when I had searched for it on a friend's device join them, many other people had the same idea, so in the end I had found it after recognizing my flag colors and member count.
Most likely many others had the same idea so I would suggest telling him how many members your clan has and what your flag looks like. If that doesn't work, I suggest making a new unique clan name only your friends would think of.
If you are not able to find the clan it could also mean that he/she is ineligible to join your clan. May be you have set a higher trophy count than your friend's. If you go to the advanced search you will find a button "Show only clans that I can join". By default its set to On. By turning it off you will be able to see all the clans matching the search keyword, provided you have searched with the proper clan name.
If this was the reason why your friend could not join you need to change settings to make it eligible.
SuperCell does not stop players from creating clans with the same name. When the player searches for a clan by its name, it may be difficult to locate the desired clan through many others with the same name. There are a few solutions:
First: give your friend information like the badge of your clan, the level, the members, and total trophies to assist him in finding your clan.
Second: give your friend your Clan Tag which he can search your clan with
Third: if your are on your friend's friends list, he can tap on your name and click View Clan