Working MO, deeply involved (8)
I believe the answer is:
employed
'working' is the definition.
('employed' can be similar in meaning to 'working')
'mo deeply involved' is the wordplay.
'involved' indicates anagramming the letters (involved can mean confusing or complex).
'mo'+'deeply'='modeeply'
'modeeply' with letters rearranged gives 'EMPLOYED'.
(Other definitions for employed that I've seen before include "Engaged - used" , "Working" , "in a job" , "Hired, made use of" , "Gave work to" .)