Very little reworking of models (6)
I believe the answer is:
seldom
'very little' is the definition.
(seldom can mean rarely or very little)
'reworking of models' is the wordplay.
'reworking of' indicates anagramming the letters (I've seen 'reworked' mean this).
'models' with letters rearranged gives 'SELDOM'.
(Other definitions for seldom that I've seen before include "Only occasionally" , "Once in a blue moon" , "Not 21" , "Not very often, rarely" , "Infrequent" .)