sample short audio clips and save to sd card as .wav

Ok, 10KHz, 10 bits.
You have 1024 words (16 bits) of SRAM. Total.
So you could store 1024 samples max.
You need 10,000 sample/sec * 5 sec = 50,000 samples.
Can you add some external memory? None of the AVR chips have enough for a 1 clip capture.