Curious and boisterous? Not I (4)
I believe the answer is:
nosy
'curious' is the definition.
(similar in meaning)
'boisterous? not i' is the wordplay.
'boisterous?' becomes 'noisy' (similar in meaning).
'not' suggests deleting specific letters.
'noisy' with 'i' removed is 'NOSY'.
'and' acts as a link.
(Other definitions for nosy that I've seen before include "Prying, snoopy" , "Inquisitive in nasal manner" , "Inclined to poke into other people's affairs" , "Over-inquisitive" , "Showing too much curiosity about people's affairs" .)