No, it's not a full compiler. It's different in a crucial respect: things it doesn't understand get passed straight out. This allows me to do most things as macros, just like you. More information: http://arclanguage.org/item?id=12814
I haven't dug into it yet, but I suspect the crucial difference might be your use of packages, which is more in line with Common Lisp idioms.
All you need is asdf 3.1.2 or later and Clamp has to be somewhere in your ~/common-lisp/ directory. Once you do that, just use (require :asdf) and (require :clamp).
I'll just include a reference to this[0] in the readme.
I get this error when running from the Clamp directory:
$ sbcl
* (require :asdf)
NIL
* (require :clamp)
ASDF could not load clamp because
Error while trying to load definition for system clamp from pathname
~/Clamp/clamp.asd:
The name "ASDF-USER" does not designate any package..
debugger invoked on a LOAD-SYSTEM-DEFINITION-ERROR in thread
#<THREAD "initial thread" RUNNING {1002998F33}>:
Error while trying to load definition for system clamp from pathname
~/Clamp/clamp.asd:
The name "ASDF-USER" does not designate any package.
Type HELP for debugger help, or (SB-EXT:QUIT) to exit from SBCL.
restarts (invokable by number or by possibly-abbreviated name):
0: [RETRY ] Retry EVAL of current toplevel form.
1: [CONTINUE ] Ignore error and continue loading file "~/Clamp/clamp.asd".
2: [ABORT ] Abort loading file "~/Clamp/clamp.asd".
3: [REINITIALIZE-SOURCE-REGISTRY-AND-RETRY] Retry finding system clamp after
reinitializing the
source-registry.
4: Exit debugger, returning to top
level.
((FLET #:LAMBDA2286 :IN ASDF::LOAD-SYSDEF)
#<SB-KERNEL:SIMPLE-PACKAGE-ERROR "The name ~S does not designate any package."
{10049EB763}>)
0]