Carroll really has to avoid losing last child (7)
I believe the answer is:
dodgson
'carroll really' is the definition.
(Lewis Carroll's real name was Charles Dodgson)
'avoid losing last child' is the wordplay.
'avoid' becomes 'dodge' (dodge can mean to avoid or evade).
'losing last' means to remove the last letter.
'child' becomes 'son' (male child).
'dodge' with its final letter taken away is 'dodg'.
'dodg'+'son'='DODGSON'
'has to' acts as a link.
(Other definitions for dodgson that I've seen before include "Victorian don" , "Carroll, really" , "Lewis Carroll's real family name" , "Writer" , "Author" .)