Small illuminated atelier regularly visited (6)
I believe the answer is:
little
'small' is the definition.
(I know that small can be written as little)
'illuminated atelier regularly visited' is the wordplay.
'illuminated' becomes 'lit' (synonyms).
'regularly visited' means one should take alternating letters (letters are taken at regular intervals).
The alternate letters of 'atelier' are 'tle'.
'lit'+'tle'='LITTLE'
(Other definitions for little that I've seen before include "Wee; minute" , "Pinkie" , "Diminutive" , "Small in size or amount" , "part of Stuart in film?" .)