Become tired at work, making large container (6)
I believe the answer is:
flagon
'large container' is the definition.
(large drinks container)
'become tired at work' is the wordplay.
'become tired' becomes 'flag' (to flag is to get tired or exhausted).
'at work' becomes 'on' (on can mean activated or working).
'flag'+'on'='FLAGON'
'making' acts as a link.
(Other definitions for flagon that I've seen before include "Large bottle for alcohol" , "Large drinks container" , "Snow White companion" , "Large round bottle as for cider" , "Large wine vessel" .)