Dusk improved with old glory (5)
I believe the answer is:
kudos
'glory' is the definition.
(I've seen this before)
'dusk improved with old' is the wordplay.
'improved with' indicates anagramming the letters.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'dusk' anagrammed with 'o' gives 'KUDOS'.
(Other definitions for kudos that I've seen before include "Pat on the back" , "Fame - prestige" , "Honour - cachet" , "Renown" , "Pats on the back" .)