Concentrated amount of work accepted by one European hotel employee (9)
I believe the answer is:
concierge
'hotel employee' is the definition.
(I've seen this before)
'concentrated amount of work accepted by one european' is the wordplay.
'concentrated' becomes 'conc' (chemical abbreviation).
'amount of work' becomes 'erg' (scientific unit for work or energy).
'accepted by' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'european' becomes 'e' (abbreviation e.g. EU).
'i'+'e'='ie'
'erg' going within 'ie' is 'ierge'.
'conc'+'ierge'='CONCIERGE'
(Other definitions for concierge that I've seen before include "One books tickets etc for hotel guests" , "Caretaker's" , "hotel employee" , "Doorkeeper of hotel or apartment building" , "Hall porter" .)