Turn on the waterworks for last shift producing endless pieces of cut glass (8)
I believe the answer is:
crystals
'endless pieces of cut glass' is the definition.
I can't judge whether this definition defines the answer.
'turn on the waterworks for last shift' is the wordplay.
'turn on the waterworks' becomes 'cry' (I've seen this in another clue).
'for' becomes 's' (I can't explain this - if you can you should give a lot more credence to this answer).
'shift' indicates anagramming the letters.
'last' with letters rearranged gives 'tals'.
'cry'+'s'+'tals'='CRYSTALS'
'producing' is the link.
Can you help me to learn more?
(Other definitions for crystals that I've seen before include "Clear transparent minerals, especially quartz" , "Try class to find pieces of high quality glass" , "Rocks formed by the solidification of a substance" , "Fragments of transparent quartz" , "Clear quartz pieces" .)