Guru before noon coming into Westminster? (5)
I believe the answer is:
swami
'guru' is the definition.
(I've seen this in another clue)
'before noon coming into westminster?' is the wordplay.
'before noon' becomes 'AM' (as in AM on a clock).
'coming into' is an insertion indicator.
'westminster?' becomes 'swi' (resembles SW1, London postcode).
'am' inserted into 'swi' is 'SWAMI'.
(Other definitions for swami that I've seen before include "Guru" , "Hindu male religious teacher" , "Religious master" , "Religious leader" , "Hindu mystic" .)