To sharpen things makes the difference after starting work (4)
I believe the answer is:
whet
'to sharpen' is the definition.
(I know this)
'the difference after starting work' is the wordplay.
'difference' indicates anagramming the letters.
'after' means one lot of letters go next to another.
'starting' indicates taking the first letters.
The first letter of 'work' is 'w'.
'the' with letters rearranged gives 'het'.
'het' after 'w' is 'WHET'.
'things makes' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for whet that I've seen before include "Make keen" , "appetizer" , "Make more acute" , "Sharpen by rubbing" , "Excite" .)