Wild kid, full of spirit (6)
I believe the answer is:
raging
'wild' is the definition.
(I know that wild can be written as raging)
'kid full of spirit' is the wordplay.
'kid' becomes 'rag' (both can mean to tease).
'full of' is an insertion indicator.
'spirit' becomes 'gin' (alcoholic spirit).
'rag' placed around 'gin' is 'RAGING'.
(Other definitions for raging that I've seen before include "(Of fire or storm) violent" , "Boiling with anger" , "Extremely angry" , "wild" , "Expressing violent anger" .)