If there's a way to narrow it down to a certain sound frequency - the frequency of hands clapping, that would work better,
A clap is an impulse and as such has a wide spectrum.
just like those "The Clapper" devices in the 90's?
Most (possibly all) of those were fake controlled by a person.
You can use an amplifier before the microphone and after that an envelope detector before feeding it into the analogue input to get an over all measure of the sound, but this is not very well correlated to the perceived loudness.
An envelope detector is a rectifier, either half or full wave with some sort of filtering - low pass filtering is the norm, however viewing a concentration of change in high frequency energy (even in a wideband signal) may be more effective. I do this all of the time to detect events using spectral means (spectral flux), but it also works in the time domain. This would prevent background noise - rumbles, voice, etc...from falsely triggering your device. The rectification can be accomplished by offsetting your ADC values by subtracting the (number of bits)^2 / 2, then giving absolute values to those below 0 (full wave rectification) or by completely truncating those values (half wave rectification) - you can then set thresholds/conditionals for onset and offset. Ensure to bandlimit your input signal to avoid strange values hitting the ADC.