No good having formally given agreement that is undated (4,3)
I believe the answer is:
sine die
'undated' is the definition.
(I've seen this before)
'no good having formally given agreement that is' is the wordplay.
I cannot quite see how this works, but
'no' could be 'n' (common abbreviation) and 'n' is located in the answer.
'that is' could be 'ie' (short for Latin 'id est', 'that is') and 'ie' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sine die that I've seen before include "For an indefinite period (Latin)" , "without a date" , "no time to make fresh start" , "indefinitely adjourned" , "With no appointed date for resumption (Latin)" .)