Turned up one over the eight during work: good start! (7)
I believe the answer is:
opening
'start' is the definition.
(opening is a kind of start)
'turned up one over the eight during work good' is the wordplay.
'turned up' shows that the letters should be reversed in order.
'one over the eight' becomes 'nine' (I've seen this before).
'during' means one lot of letters goes inside another.
'work' becomes 'op' (abbreviation for opus).
'good' becomes 'g' (abbreviation).
'nine' in reverse letter order is 'enin'.
'op'+'g'='opg'
'enin' inserted inside 'opg' is 'OPENING'.
(Other definitions for opening that I've seen before include "Opportunity; gap" , "Aperture or first night" , "Rent" , "First -- beginning" , "break" .)