Enjoyable bit of lunch with a leader of fashion (3)
I believe the answer is:
fun
'enjoyable' is the definition.
(fun means enjoyable or pleasing)
'bit of lunch with a leader of fashion' is the wordplay.
'bit of lunch' becomes 'un' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'with' is a charade indicator (letters next to each other).
'a leader of' says to take the initial letters.
The initial letter of 'fashion' is 'f'.
'un' put after 'f' is 'FUN'.
Can you help me to learn more?
(Other definitions for fun that I've seen before include "Enjoyment" , "Light-hearted amusement, jollity" , "'Merriment, playfulness (3)'" , "Entertaining" , "Jollification" .)