Discusses how to beat Des up (7)
I believe the answer is:
debates
'discusses' is the definition.
(debating is a kind of discussing)
'to beat des up' is the wordplay.
'up' indicates anagramming the letters (letters get chucked up).
'beat'+'des'='beatdes'
'beatdes' with letters rearranged gives 'DEBATES'.
'how' acts as a link.
(Other definitions for debates that I've seen before include "Discusses" , "Formal discussions" .)