Speed unions insist upon to get the job done (4)
I believe the answer is:
rate
'speed' is the definition.
(the speed at which something happens)
'unions insist upon to get the job done' is the wordplay.
I cannot really see how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
The remaining letters 'rae' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for rate that I've seen before include "Cost" , "Think highly of - price" , "standard levy" , "Assign a value to, appraise" , "Be worthy of, merit" .)