Parcel contains voided ticket for Waterloo? (6)
I believe the answer is:
battle
'waterloo?' is the definition.
(waterloo is a kind of battle)
'parcel contains voided ticket' is the wordplay.
'parcel' becomes 'bale' (bale is a kind of parcel).
'contains' indicates putting letters inside.
'voided' means to remove the middle letters (void can mean to empty out).
'ticket' with its middle removed is 'tt'.
'bale' going around 'tt' is 'BATTLE'.
'for' acts as a link.
(Other definitions for battle that I've seen before include "- - of 5 down" , "Naval engagement" , "Difficult conflict or struggle" , "Armed conflict" , "A fight between large forces" .)