Lady (5)
'lady' is the definition.
(I know that lady can be written as woman)
This is the entire clue.
(Other definitions for woman that I've seen before include "Lady" , "With 1a [OLD], one's rather timid" , "See 16" , "person not going on stag-night" , "Mature female" .)
(Other definitions for gaga that I've seen before include "Slightly mad (colloq.)" , "Foolishly doting" , "dotty" , "Bats" , "Slangily crazy or senile" .)
'lady' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for gal that I've seen before include "Young woman (colloq.)" , "Girl from American west" , "An American girl, cowboy vintage" , "miss" , "US female" .)