Prince Andrew's defence? Nothing to it! (2,5)
I believe the answer is:
no sweat
'prince andrew's defence?' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.
'nothing to it' is the wordplay.
'nothing' becomes 'no' (similar in meaning).
'to it' becomes 'sweat' (I am not sure about this - if you are sure you should believe this answer much more).
'no'+'sweat'='NO SWEAT'
Can you help me to learn more?
(Other definitions for no sweat that I've seen before include "fine" , "East won (anag)" , "That's not a problem!" , "That's a piece of cake (anti-perspirant unnecessary!)" , "There shouldn't be any objection" .)