Work out with copper in US state after the usual time (9)
I believe the answer is:
calculate
'work out' is the definition.
(I've seen this before)
'copper in us state after the usual time' is the wordplay.
'copper' becomes 'cu' (chemical symbol).
'in' is an insertion indicator.
'us state' becomes 'Cal' (abbreviation for California).
'after the usual time' becomes 'late' (I've seen this before).
'cal'+'late'='callate'
'cu' inserted inside 'callate' is 'CALCULATE'.
'with' acts as a link.
(Other definitions for calculate that I've seen before include "'Work out, compute (9)'" , "Determine mathematically" , "Solve by mathematical procedure" , "Compute or reckon" , "Think about" .)