Fancies deranged from the start - isn't the sharpest tool in the box (7)
I believe the answer is:
'fancies deranged from the start isn't the sharpest tool in the box' is the definition.
I can't tell whether this defines the answer.
'fancies deranged from the start isn't the sharpest tool in' is the wordplay.
'fancies' becomes 'bit' (I can't explain this - if you can you should believe this answer much more).
'deranged' indicates anagramming the letters.
'from the start' indicates taking the first letters.
'in' is an insertion indicator.
The initial letters of 'isnt the sharpest tool' is 'itst'.
'itst' with letters rearranged gives 'tits'.
'bit' put within 'tits' is 'TITBITS'.
Can you help me to learn more?
(Other definitions for titbits that I've seen before include "Interesting snippets" , "juicy morsels" , "Choice morsels of food" .)