Type of combat in which manure is thrown by duke? (7)
I believe the answer is:
unarmed
'type of combat' is the definition.
(I've seen this before)
'manure is thrown by duke?' is the wordplay.
'is thrown' indicates an anagram (letters thrown around).
'by' means one lot of letters go next to another.
'duke?' becomes 'd' (abbreviation).
'manure' anagrammed gives 'unarme'.
'unarme'+'d'='UNARMED'
'in which' is the link.
(Other definitions for unarmed that I've seen before include "Lacking a weapon" , "Weaponless" , "Like Venus de Milo" , "Type of combat" , "Defenceless" .)