Registered nurse extremely upset with older criminal stealing a pound (8)
I believe the answer is:
enrolled
'registered nurse' is the definition.
'enrolled' can be an answer for 'registered' (enrolling is a kind of registering). I'm not certain of the 'nurse' bit.
'extremely upset with older criminal stealing a pound' is the wordplay.
'extremely upset' becomes 'en' (I can't explain this - if you can you should give a lot more credence to this answer).
'with' means one lot of letters go next to another.
'criminal' indicates an anagram.
'stealing' indicates putting letters inside.
'a pound' becomes 'L' (the pound sign is based on an L).
'older' with letters rearranged gives 'roled'.
'roled' enclosing 'l' is 'rolled'.
'en'+'rolled'='ENROLLED'
(Other definitions for enrolled that I've seen before include "Registered as a member" , "being on board submarine?" , "Admitted" , "Registered as a participant" , "Officially registered" .)