Increase resistance in material for building houses (9)
I believe the answer is:
increment
'increase' is the definition.
(I know that increase can be written as increment)
'resistance in material for building houses' is the wordplay.
'resistance' becomes 'r' (electronics abbreviation).
'material for building' becomes 'cement' (I can't explain this - if you can you should believe this answer much more).
'houses' is an insertion indicator.
'in'+'cement'='incement'
'r' going within 'incement' is 'INCREMENT'.
Can you help me to learn more?
(Other definitions for increment that I've seen before include "Addition to wages etc" , "Increase (one of a series)" , "Small change" , "Amount by which something increases" , "Small addition to salary etc" .)