Hail enters two points in part of roof (5)
I believe the answer is:
eaves
'part of roof' is the definition.
('eaves' is part of 'roof')
'hail enters two points' is the wordplay.
'two points' can mean two substitutions for 'point'.
'hail' becomes 'ave' (I've seen this before).
'enters' indicates putting letters inside.
'point' becomes 'e' (E is an example**).
'point' becomes 's'.
'e'+'s'='es'
'ave' put into 'es' is 'EAVES'.
'in' is the link.
(Other definitions for eaves that I've seen before include "Projecting edge of a roof" , "Overhanging edge of roof" , "Overhanging roof edges" , "Part of a building's roof that overhangs the walls" , "what might constitute a hangover?" .)