A task to put metal in the street (5)
I believe the answer is:
stint
'a task' is the definition.
(I know that stint is a type of task)
'metal in the street' is the wordplay.
'metal' becomes 'tin' (tin is a kind of metal).
'in the' is an insertion indicator.
'street' becomes 'st' (abbreviation).
'tin' going inside 'st' is 'STINT'.
'to put' acts as a link.
(Other definitions for stint that I've seen before include "Fixed amount - allowance" , "Stretch; be miserly" , "Spare" , "Restrict to small allowance, be niggardly" , "Stretch of work" .)