One died in fight — but when? (6)
I believe the answer is:
friday
'when?' is the definition.
(I've seen this before)
'one died in fight' is the wordplay.
'one' becomes 'i' (Roman numeral).
'died' becomes 'd' (abbreviation next to the year of someone's death).
'in' means one lot of letters goes inside another.
'fight' becomes 'fray' (fray is a kind of fight).
'i'+'d'='id'
'id' inserted into 'fray' is 'FRIDAY'.
'but' acts as a link.
(Other definitions for friday that I've seen before include ""Good" day at Easter?" , "An islander" , "One of seven" , "God is thanked for this" , "Crusoe's companion" .)