Name jerk admitting single currency is unstable (8)
I believe the answer is:
neurotic
'unstable' is the definition.
(thesaurus)
'name jerk admitting single currency' is the wordplay.
'name' becomes 'n' (common abbreviation e.g. on forms).
'jerk' becomes 'tic' (I've seen this before).
'admitting' is an insertion indicator.
'single currency' becomes 'euro' (I've seen this before).
'n'+'tic'='ntic'
'ntic' going around 'euro' is 'NEUROTIC'.
'is' is the link.
(Other definitions for neurotic that I've seen before include "Paranoid" , "Very anxious and stressed" , "Subject to excessive anxiety and behaviour" , "Emotionally disturbed" , "As I recount being subject to abnormal anxieties" .)