Aim at office worker on short time (7)
I believe the answer is:
Here is my best explanation:
'aim' is the definition.
'at office worker on short time' is the subsidiary indication.
'office worker' becomes 'temp' (I've seen this in other clues).
'on' is a charade indicator (letters next to each other).
'short' indicates taking the first letters.
The first letter of 'time' is 't'.
(Other definitions for attempt that I've seen before include "Have a crack", "Try, hazard", "Endeavor, try", "Try, endeavour", "Try to climb (a peak)", "Effort; go", "Bid", "Try, make an effort", "Essay" and "Tackle".)