Expand new detail (6)
I believe the answer is:
dilate
'expand' is the definition.
(thesaurus)
'new detail' is the wordplay.
'new' indicates an anagram.
'detail' anagrammed gives 'DILATE'.
(Other definitions for dilate that I've seen before include "Get bigger" , "Enlarge - detail (anag)" , "Widen, distend" , "contract? No" , "Make wider or larger" .)