Musical effect that's a lot more fluttery? (7)
'musical effect' is the definition.
(I've seen this before)
'a lot more fluttery?' is the wordplay.
'lot more' anagrams to 'TREMOLO'.
Though, I'm not clear how the anagram is indicated.
'that's' is the link.
Can you help me to learn more?
(Other definitions for tremolo that I've seen before include "Vibrato effect", "Vocal vibrato -- lot more (anag)", "A vibrating effect in music", "Violin's rapid repetition of a single note", "Quivering musical effect".)