Need advice on how to get a feral cat who is not fond of people caught and submissive so I can try to groom her very matted coat. Any suggestions please?
I just took my very matted feral cat to the vet for several reasons. Grooming him was one of the things they did, probably while he was anesthetized for tooth cleaning. He had to be shaved in several spots to get the mats off. It's not something I'd ever have been able to do for him.
Do you think your girl will let you use clippers on her? Combing will be terribly painful and could cause skin injuries.
I'd trap as you would for TNR and take to vet. Warn the vet ahead of time of what you need. They may have special staff, or a particular person who does the grooming.
If you do plan to try to shave him yourself, you will need electric clippers, the casing for them is about twice the length of your hand. If you use scissors you will inevitably nick the cat, who will not react well. If you don't sedate the cat, again the cat will not react well. Removing mats is a bit painful and the cat considers it an attack. This is true even if the cat has known you from its birth.
But if you feel you can do it, you'll need to practice a bit on a willing cat so you won't pull his mats when working on him. This is actually difficult to do on a non-feral. I took our not feral long haired cats in once a year to be lightly sedated and shaved - they left the head, neck, legs and tail unshaved. They looked excellent.
If you can't brush a cat, you aren't going to be able to shave it unsedated. But you are a good person for looking for a solution. In time, that poor feral would not be able to walk and would be damaging his skin.