That girl's free article for boy (8)
I believe the answer is:
sheridan
'boy' is the definition.
'that girl's free article' is the wordplay.
'that girl' becomes 'she' ('she' refers to a woman).
'free' becomes 'rid' (to be free of something is to be rid of it).
'article' becomes 'an' (indefinite article).
'she'+'rid'+'an'='SHERIDAN'
'for' acts as a link.
(Other definitions for sheridan that I've seen before include "general, esteemed by Americans" , "Creator of Mrs Malaprop in The Rivals" , "School for Scandal playwright" , "The Rivals author" , "Richard Brinsley ........, Anglo-Irish author of ` `The School for Scandal' '" .)