Thinks tragedy out of order — prospect of a fine day? (3,3,2,5)
I believe the answer is:
red sky at night
'prospect of a fine day?' is the definition.
('red sky at night - shepherd's delight')
'thinks tragedy out of order' is the wordplay.
'out of order' indicates an anagram.
'thinks'+'tragedy'='thinkstragedy'
'thinkstragedy' with letters rearranged gives 'RED SKY AT NIGHT'.
(Other definitions for red sky at night that I've seen before include "sign of good things on the morrow?" , "Shepherd's delight" .)