Fixed on Titian nude's powerful body (6,7)
I believe the answer is:
united nations
'powerful body' is the definition.
'united nations' can be an answer for 'body' (I've seen this before). I'm not sure about the 'powerful' bit.
'fixed on titian nude's' is the wordplay.
'fixed' indicates an anagram.
'on'+'titian'+'nudes'='ontitiannudes'
'ontitiannudes' is an anagram of 'UNITED NATIONS'.
Can you help me to learn more?
(Other definitions for united nations that I've seen before include "body" , "peace group" , "International peace-keeping organisation" , "International peace organisation, founded 1945 in San Francisco" , "global organisation" .)