Cut back on masonry initially dumped in builder’s container (5)
I believe the answer is:
skimp
'cut back' is the definition.
(I've seen this in another clue)
'masonry initially dumped in builder's container' is the wordplay.
'initially' suggests taking the first letters.
'dumped in' means one lot of letters goes inside another.
'builder's container' becomes 'skip' (container for construction waste).
The first letter of 'masonry' is 'm'.
'm' going within 'skip' is 'SKIMP'.
'on' acts as a link.
(Other definitions for skimp that I've seen before include "Use less to economise" , "Provide too few resources on grounds of economy" , "Limit in quality or quantity" , "Be parsimonious, stint" , "Subsist on very little" .)