Musically, everyone initially thinks ukuleles tear it up (5)
I believe the answer is:
tutti
'musically everyone' is the definition.
I can't judge whether this defines the answer.
'initially thinks ukuleles tear it up' is the wordplay.
'initially' suggests taking the first letters.
'up' says the letters should be written backwards (in down clue: letters go upwards).
The initial letters of 'thinks ukuleles tear' is 'tut'.
'it' back-to-front is 'ti'.
'tut'+'ti'='TUTTI'
Can you help me to learn more?
(Other definitions for tutti that I've seen before include "With all playing together (music)" , "Passage using all instruments" , "With all instruments twenty four Acdn (music)" , "musical direction" , "(Musically) performed by all instruments" .)