Duel with aunt, possibly, and wave (8)
I believe the answer is:
undulate
'wave' is the definition.
(I know that wave can be written as undulate)
'duel with aunt possibly' is the wordplay.
'with' means one lot of letters go next to another.
'possibly' is an anagram indicator.
'duel' after 'aunt' is 'auntduel'.
'auntduel' with letters rearranged gives 'UNDULATE'.
'and' acts as a link.
(Other definitions for undulate that I've seen before include "wave" , "make waves" , "Have wavy movement or appearance" , "Move with a rising and falling motion" , "Have a wavy outline" .)