Blood-sucker finding shelter by church (5)
I believe the answer is:
leech
'blood-sucker' is the definition.
(I've seen this before)
'shelter by church' is the wordplay.
'shelter' becomes 'lee' (as in lee side, the side sheltered from wind).
'by' says to put letters next to each other.
'church' becomes 'ch' (common abbreviation).
'lee'+'ch'='LEECH'
'finding' is the link.
(Other definitions for leech that I've seen before include "Blood-sucking parasite" , "Parasite - hanger-on" , "Small worm once used for blood-letting, or a parasitical person" , "Medicinal bloodsucker" , "Blood-sucking worm or parasitic person" .)