Guy left behind eastern place of worship (6)
I believe the answer is:
chapel
'place of worship' is the definition.
(chapel is a kind of place of worship)
'guy left behind eastern' is the wordplay.
'guy' becomes 'chap' (both can mean a man).
'left' becomes 'l' (common abbreviation).
'behind' means one lot of letters go next to another.
'eastern' becomes 'e'.
'l' put after 'e' is 'el'.
'chap'+'el'='CHAPEL'
(Other definitions for chapel that I've seen before include "Might he clap in the place of worship?" , "union group" , "Local printers" , "service" , "Nonconformist church" .)