Chances of delightful day slim at the front (4)
I believe the answer is:
odds
'chances' is the definition.
(I've seen this before)
'of delightful day slim at the front' is the wordplay.
'at the front' indicates taking the first letters.
The initial letters of 'of delightful day slim' is 'ODDS'.
(Other definitions for odds that I've seen before include "They could be evens" , "Gambler's chances" , "Probabilities" , "(In betting) chances" , "prices" .)