He's something of a local eccentric (4)
I believe the answer is:
alec
'he's' is the definition.
(I've seen this before)
'something of a local eccentric' is the wordplay.
'something of' indicates a hidden word (I've seen 'something' mean this (I've seen this in other clues)).
'ALEC' can be found hidden inside 'local eccentric'.
(Other definitions for alec that I've seen before include "Smart man?" , "Smart chap" , "A smart . . . . is a know-all in lace" , "Sir -- Guinness, actor" , "Smart boy?" .)