Timber used in rural architecture (5)
I believe the answer is:
larch
'timber' is the definition.
(I've seen this before)
'in rural architecture' is the wordplay.
'in' indicates the answer is hidden within the clue.
'LARCH' can be found hidden inside 'rural architecture'.
'used' acts as a link.
(Other definitions for larch that I've seen before include "Coniferous tree with deciduous bright green needles" , "wood" , "Supplier of timber" , "Deciduous conifer" .)