There’s more to it than the linker, especially if you want to support real mode. You need a DOS C library, and a compiler which can output 16-bit code. If you want to produce binaries in anything other than the tiny model, you also need a compiler that’s aware of segmentation.
As far as I’m aware, clang doesn’t have the necessary features. There are a few other possibilities:
Open Watcom can produce 16-bit real-mode and 32-bit protected-mode DOS programs (if you’re interested in Open Watcom, you probably want the unofficial v2 fork)
DJGPP produces 32-bit protected-mode DOS programs
gcc-ia16 produces 16-bit real-mode DOS programs
For the latter two, I recommend jwt27’s build scripts which will install complete ia16 and DJGPP toolchains, including a DOS C library.
Most modern C compilers targeting DOS 8086, running on DOS 8086 (16-bit) gives a comprehensive list of DOS-targeting compilers; most of them require a DOS or Windows host.