Qmake - clear additional subdir

Question

I have a Qt 4.8 project with subdir. I installed the * .pro file to create the lib library in this directory in order to use it in the core of my application. It works well.

The subdirectory uses the usual Makefile.

Now I'm trying to add the ability to clear this subdirectory by calling a clean command in the library's Makefile.

Here is what I got now:

LIBS = bin/libfoo.a
QMAKE_EXTRA_TARGETS += somelib

# some lib
PRE_TARGETDEPS += somelib
somelib.commands = make -C lib/somelib LIB=../../bin/libfoo.a lib
somelib.clean_commands = make -C lib/somelib clean

I have no problem compiling my project with this lib.

But when I run "make clean" on the qmake Makefile created, "make -C lib / somelib clean" is not called.

How can i achieve this?