Sees anger transforming into anxiety (9)
I believe the answer is:
eagerness
'anxiety' is the definition.
(thesaurus)
'sees anger transforming' is the wordplay.
'transforming' is an anagram indicator (I've seen 'transform' mean this).
'sees'+'anger'='seesanger'
'seesanger' anagrammed gives 'EAGERNESS'.
'into' is the link.
(Other definitions for eagerness that I've seen before include "Avidity" , "Sense rage (anag.)" , "Keenness, enthusiasm" , "'Keenness, avidness (9)'" , "Keen interest" .)