English lawyer upset training expert (5)
I believe the answer is:
adept
'expert' is the definition.
('adept' can be a synonym of 'expert')
'english lawyer upset training' is the wordplay.
'english' becomes 'e' (abbreviation).
'lawyer' becomes 'da' (D.A. is an example).
'upset' shows that the letters should be reversed in order.
'training' becomes 'pt'.
'e'+'da'='eda'
'eda' in reverse letter order is 'ade'.
'ade'+'pt'='ADEPT'
(Other definitions for adept that I've seen before include "One highly skilled could be taped" , "Taped (anag.)" , "Dexterous" , "Handy" , "Deacon" .)