Skilful fables, with no head or tail (4)
I believe the answer is:
able
'skilful' is the definition.
(I've seen this before)
'fables with no head or tail' is the wordplay.
'with no head or tail' indicates the central letters (the head and tail of the word are removed).
The centre of 'fables' is 'ABLE'.
(Other definitions for able that I've seen before include "Clever skilful" , "Well-equipped" , "Competent - sort of seaman" , "accomplished" , "Bale out, being competent" .)