The King has a fine reproduction dagger (5)
I believe the answer is:
knife
'dagger' is the definition.
(I've seen this before)
'the king has a fine reproduction' is the wordplay.
'the king' becomes 'K' (abbreviation for king in chess).
'has' says to put letters next to each other.
'reproduction' indicates anagramming the letters.
'fine' with letters rearranged gives 'nife'.
'k'+'nife'='KNIFE'
(Other definitions for knife that I've seen before include "Use this to carve" , "Eating utensil" , "Dagger" , "Table implement" , "Cutting utensil" .)