Having stopped work to eat bananas (3,2,5)
I believe the answer is:
out to lunch
'bananas' is the definition.
(I've seen this in another clue)
'having stopped work to eat' is the wordplay.
'having stopped work' becomes 'outto' (I can't explain this - if you can you should believe this answer much more).
'to eat' becomes 'lunch' (lunching is a kind of eating).
'outto'+'lunch'='OUT TO LUNCH'
Can you help me to learn more?
(Other definitions for out to lunch that I've seen before include "unhinged?" , "Temporarily removed from office" , "unbalanced" , "being served in restaurant perhaps" , "Crackers" .)