It's most sharply contested, though one doesn't win in court (7)
I believe the answer is:
closest
'it's most sharply contested' is the definition.
I can't judge whether this definition defines the answer.
'one doesn't win in court' is the wordplay.
'one doesn't win' becomes 'loses' (I've seen this in another clue).
'in' means one lot of letters goes inside another.
'court' becomes 'ct' (abbreviation used in road names).
'loses' put into 'ct' is 'CLOSEST'.
'though' is the link.
Can you help me to learn more?
(Other definitions for closest that I've seen before include "Superlatively dense" , "Nearest or meanest" , "Nearest or most sultry" , "Most intimate" , "Most secretive" .)