Complicated work in America in each telephone exchange, initially (9)
I believe the answer is:
'complicated' is the definition.
(I've seen this before)
'work in america in each telephone exchange initially' is the wordplay.
'work in america' becomes 'labor' (US spelling of 'labour').
'in' means one lot of letters goes inside another.
'each' becomes 'ea' (abbreviation).
'initially' suggests taking the first letters.
The first letters of 'telephone exchange' is 'te'.
'labor' inserted into 'ea' is 'elabora'.
(Other definitions for elaborate that I've seen before include "With many parts or details, maybe a pattern" , "Complicated - complex" , "with added detail" , "Intricate - ornament" , "very busy" .)