She is a relatively fair target? (4,5)
I believe the answer is:
aunt sally
'fair target?' is the definition.
(I've seen this before)
'she is a relatively' is the wordplay.
'she' becomes 'aunt' ('she' could refer to an aunt).
'is a relatively' becomes 'sally' (I am not sure about this - if you are sure you should believe this answer much more).
'aunt'+'sally'='AUNT SALLY'
(Other definitions for aunt sally that I've seen before include "Target for abuse" , "She's a target in throwing games, like female relative" , "Fair target" , "Target of general criticism, as in throwing game" , "Shy" .)