Make known girl's weight (8)
I believe the answer is:
announce
'make known' is the definition.
(synonyms)
'girl's weight' is the wordplay.
'girl' becomes 'ann' (woman's name).
'weight' becomes 'ounce' (ounce is a kind of weight).
'ann'+'ounce'='ANNOUNCE'
(Other definitions for announce that I've seen before include "Disclose" , "Declare publicly" , "Make known, declare" , "Give public notice to" , "Publicise" .)