Man in Hornchurch apartment (4)
I believe the answer is:
chap
'man' is the definition.
(term for a man)
'in hornchurch apartment' is the wordplay.
'in' indicates a hidden word.
'CHAP' is hidden within 'hornchurch apartment'.
(Other definitions for chap that I've seen before include "Cracked skin patch caused by cold" , "Become raw from cold - fellow" , "Man, boy, fellow" , "Man, sore patch" , "Fellow; sore skin area" .)