Measures one leaves to endanger (7)
I believe the answer is:
imperil
'to endanger' is the definition.
('imperil' can be a synonym of 'endanger')
'measures one' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'er' (I've seen this in other clues) and 'er' is present in the answer.
This may be the basis of clue (or it may be nonsense).
'leaves' acts as a link.
Can you help me to learn more?
(Other definitions for imperil that I've seen before include "Jeopardize" , "Put at risk" , "Place in danger" , "Threaten, jeopardise" , "Put in danger" .)