Women love ordering about - I for one (5)
I believe the answer is:
vowel
'i for one' is the definition.
(I is an example of a vowel)
'women love ordering about' is the wordplay.
'women' becomes 'w' (standard abbreviation).
'ordering' is an anagram indicator.
'about' means one lot of letters goes inside another.
'love' anagrammed gives 'voel'.
'w' placed into 'voel' is 'VOWEL'.
(Other definitions for vowel that I've seen before include "Letter such as i or u" , "Letter representing sound" , "Open sound in speech" , "aeio or u" , "O for one" .)