There are a few apps that can help identify individual instruments in music, although they might not be as common as song recognition apps. One app you could try is "Instrument Identifier" by Prasad Jangam. It's available on the App Store and claims to identify instruments in a song. Another option is to use a music production software like Ableton Live, which has audio-to-MIDI conversion features that can help identify individual instruments in a mix. Additionally, some music theory apps offer instrument identification quizzes, which could also help you train your ear to recognize different
instruments.