Complex work in America accepted by consumer - mostly! (9)
I believe the answer is:
Here is my best explanation:
'complex' is the definition.
'work in america accepted by consumer mostly' is the wordplay.
'work in america' becomes 'labor' (I've seen this in other clues).
'accepted by' means one lot of letters goes inside another.
'consumer' becomes 'eater' (eater is a kind of consumer).
'mostly' means to remove the last letter.
'eater' with its last letter removed is 'eate'.
'labor' placed inside 'eate' is 'ELABORATE'.