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 "Try to climb (a peak)", "Tackle", "Try, hazard", "Try, endeavour", "Endeavour, try", "Endeavor, try", "Stab", "Make an effort", "Have a crack" and "Effort; go".)