What does the cryptic crossword clue "Friends upset over wicked-sounding guitar technique (4,4)" mean?

The definition is "guitar technique". The wordplay uses a homophone (sounds like). PALS upside-down + sounds like BASE. The answer is SLAP BASS.

Friends upset over wicked-sounding guitar technique (4,4)

Times Cryptic #28591 | 17 Down | 2023-05-01 flower