When Dai was bent on taking cook out for the day (6)
I believe the answer is:
friday
'when' is the definition.
(I've seen this before)
'dai was bent on taking cook out for the day' is the wordplay.
I cannot quite see how this works, but
an anagram of 'dai' is 'ida' which is present in the answer.
'cook' could be 'fry' (frying is a type of cooking) and 'fry' is found within the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for friday that I've seen before include "Muslim Sabbath" , ""Good" day at Easter?" , "It's payday for some" , "Robinson Crusoe's manservant" , "Crusoe's companion" .)