Lively, loud, and dangerous (6)
I believe the answer is:
frisky
'lively' is the definition.
(I've seen this before)
'loud and dangerous' is the wordplay.
'loud' becomes 'f' (A musical term).
'and' means one lot of letters go next to another.
'dangerous' becomes 'risky' ('risky' can be similar in meaning to 'dangerous').
'f'+'risky'='FRISKY'
(Other definitions for frisky that I've seen before include "Energetically playful" , "High-spirited" , "Animated" , "Playful, full of energy" , "Frolicsome" .)