Woman's soiree regularly involving us (5)
I believe the answer is:
susie
'woman's' is the definition.
(woman's name)
'soiree regularly involving us' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'involving' indicates putting letters inside.
The alternate letters of 'soiree' are 'sie'.
'sie' going around 'us' is 'SUSIE'.
(Other definitions for susie that I've seen before include "Tongue-twister sister sewing shirts for soldiers" , "Girl's name" , "Girl" , "Woman" , "Little Susannah" .)