Crossword Genius

Legal action once, when reservoir location not finalised (9)

Ross

I believe the answer is:

assumpsit

'legal action once' is the definition.
(historical type of legal action)

'when reservoir location not finalised' is the wordplay.
'when' becomes 'as'.
'reservoir' becomes 'sump' (sump is a kind of reservoir).
'location' becomes 'site' (site is a kind of location).
'not finalised' means to remove the last letter.
'site' with its final letter taken away is 'sit'.
'as'+'sump'+'sit'='ASSUMPSIT'

I've seen this clue in The Times.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.