Tennis score took day to work out (6)
I believe the answer is:
deduce
'work out' is the definition.
(I've seen this before)
'tennis score took day' is the wordplay.
I cannot quite see how this works, but
'day' could be 'd' (abbreviation for day) and 'd' is found in the answer.
The remaining letters 'educe' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
'to' acts as a link.
Can you help me to learn more?
(Other definitions for deduce that I've seen before include "Arrive at conclusion through logic" , "Infer from the evidence" , "Reason through logic" , "Draw conclusion" , "Figure out as Sherlock did" .)