Golf equipment up in Westminster European finds dear (7)
I believe the answer is:
sweetie
'dear' is the definition.
(both are terms of endearment)
'golf equipment up in westminster european' is the wordplay.
'golf equipment' becomes 'tee' (tee is a kind of golf equipment).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'in' means one lot of letters goes inside another.
'westminster' becomes 'swi' (resembles SWt, London postcode).
'european' becomes 'e' (abbreviation e.g. EU).
'tee' back-to-front is 'eet'.
'eet' going inside 'swi' is 'sweeti'.
'sweeti'+'e'='SWEETIE'
'finds' acts as a link.
(Other definitions for sweetie that I've seen before include "Maybe boyfriend" , "honey" , "Love" , "Darling" , "treasure?" .)