Repairing garage, get building material (9)
I believe the answer is:
aggregate
'material' is the definition.
(I know that aggregate is a type of material)
'repairing garage get' is the wordplay.
'repairing' indicates anagramming the letters (the order is repaired).
'garage'+'get'='garageget'
'garageget' with letters rearranged gives 'AGGREGATE'.
'building' acts as a link.
(Other definitions for aggregate that I've seen before include "ingredients of concrete" , "All - broken stone put in cement" , "Total of several separate elements" , "Material to make concrete, mortar, or plaster" , "Sum total" .)