Silly ladies' man, sort displaying ineptitude (13)
I believe the answer is:
maladroitness
'ineptitude' is the definition.
(I know that ineptitude can be written as maladroitness)
'silly ladies' man sort' is the wordplay.
'silly' indicates anagramming the letters.
'ladies'+'man'+'sort'='ladiesmansort'
'ladiesmansort' anagrammed gives 'MALADROITNESS'.
'displaying' is the link.
(Other definitions for maladroitness that I've seen before include "Clumsy behaviour" , "insensitivity" , "Clumsiness" .)