Clever stories have no introduction or conclusion (4)
I believe the answer is:
able
'clever' is the definition.
(able can mean skilled or talented)
'stories have no introduction or conclusion' is the wordplay.
'stories' becomes 'fables' (fable is a kind of story).
'have no introduction or conclusion' says to take the centre (first and last letters removed).
The central letters of 'fables' are 'ABLE'.
(Other definitions for able that I've seen before include "With the required capacities" , "Competent as seaman may be" , "In a position or competent to" , "showing talent" , "Proficient; skilful" .)