A civet can be so lively! (6)
I believe the answer is:
active
'lively' is the definition.
(similar in meaning)
'a civet can be' is the wordplay.
'can be' indicates an anagram.
'civet' is an anagram of 'ctive'.
'a'+'ctive'='ACTIVE'
'so' acts as a link.
(Other definitions for active that I've seen before include "Involved with sports" , "Vigorously moving" , "Keeping busy or operative" , "(Of mind) alert, lively" , "Busy, not idle" .)