Child friend? Absolutely (7)
I believe the answer is:
totally
'absolutely' is the definition.
('totally' can be a synonym of 'absolutely')
'child friend?' is the wordplay.
'child' becomes 'tot' (I've seen this before).
'friend?' becomes 'ally' ('ally' can be a synonym of 'friend').
'tot'+'ally'='TOTALLY'
(Other definitions for totally that I've seen before include "perfectly" , "Completely, entirely" , "without reserve" , "Altogether" , "To the full extent" .)