Children wearing zero fabric (5)
I believe the answer is:
chino
'fabric' is the definition.
(chino is a kind of fabric)
'children wearing zero' is the wordplay.
'children' becomes 'ch' (genealogical abbreviation).
'wearing' becomes 'in' (wear in (and 'in' is fashionable)).
'zero' becomes 'o'.
'ch'+'in'+'o'='CHINO'
(Other definitions for chino that I've seen before include "Coarse cotton khaki-coloured fabric" , "Coarse twilled cotton fabric" , "American material" , "strong cloth" , "Durable cotton fabric" .)