Advanced section, highly skilled (5)
I believe the answer is:
adept
'highly skilled' is the definition.
(I've seen this before)
'advanced section' is the wordplay.
'advanced' becomes 'a' (abbreviation).
'section' becomes 'dept' (short for department).
'a'+'dept'='ADEPT'
(Other definitions for adept that I've seen before include "One highly skilled could be taped" , "Taped (anag.)" , "Showing skill or aptitude" , "Skilful and adroit" , "Thoroughly proficient" .)