Not as many women going in free? Rubbish! (5)
I believe the answer is:
fewer
'not as many' is the definition.
('few' can be the opposite of 'many' so perhaps 'fewer' is reasonable for 'not as many')
'women going in free? rubbish' is the wordplay.
'women' becomes 'w'.
'going in' is an insertion indicator.
'rubbish' is an anagram indicator (a poor quality or rubbish spelling of the letters).
'free' anagrammed gives 'feer'.
'w' placed within 'feer' is 'FEWER'.
(Other definitions for fewer that I've seen before include "smaller number of people" , "Less in number" , "Not so many" , "Reduced" , "in smaller numbers" .)