Which church must get roofing material? (6)
I believe the answer is:
thatch
'roofing material?' is the definition.
(thatch is a kind of roofing material)
'which church' is the wordplay.
'which' becomes 'that'.
'church' becomes 'ch' (common abbreviation).
'that'+'ch'='THATCH'
'must get' is the link.
(Other definitions for thatch that I've seen before include "Natural roof cover" , "Old fashioned rural roof covering" , "Plant stalks as roofing material" , "top-level cover" , "Old-fashioned roofing material" .)