Nun is pale, shaking head (9)
I believe the answer is:
peninsula
'head' is the definition.
(thesaurus)
'nun is pale shaking' is the wordplay.
'shaking' indicates anagramming the letters.
'nun'+'is'+'pale'='nunispale'
'nunispale' with letters rearranged gives 'PENINSULA'.
(Other definitions for peninsula that I've seen before include "Lower California, say" , "Alpine sun (anag.)" , "Malay for one" , "the Balkans and Italy, for example" , "coastal feature" .)