Sucker expecting shelter to be offered by church (5)
I believe the answer is:
leech
'sucker' is the definition.
(I've seen this in another clue)
'shelter to be offered by church' is the wordplay.
'shelter' becomes 'lee' (as in lee side, the side sheltered from wind).
'to be offered by' means one lot of letters go next to another.
'church' becomes 'ch' (common abbreviation).
'lee'+'ch'='LEECH'
'expecting' is the link.
This may not be right. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for leech that I've seen before include "Parasite - hanger-on" , "Proverbial bloodsucker" , "Blood-sucking worm or parasitical person" , "one good at sponging" , "Old doctor" .)