Unhappiness caused by penny-pincher at end of holiday (6)
I believe the answer is:
misery
'unhappiness' is the definition.
(I've seen this before)
'penny-pincher at end of holiday' is the wordplay.
'penny-pincher' becomes 'miser' (I've seen this before).
'at end of' indicates one should take the final letters.
The last letter of 'holiday' is 'y'.
'miser'+'y'='MISERY'
'caused by' acts as a link.
(Other definitions for misery that I've seen before include "Despair" , "Party-pooper" , "Wretched state" , "Intense unhappiness" , "Wretched unhappiness" .)