Herb used sparely (7)
I believe the answer is:
parsley
'herb' is the definition.
(parsley is a kind of herb)
'used sparely' is the wordplay.
'used' is an anagram indicator.
'sparely' is an anagram of 'PARSLEY'.
(Other definitions for parsley that I've seen before include "Cow -, fool's - and stone - are all plants" , "Use the herb sparely" , "Food-flavouring herb for players" , "Culinary herb" , "Herb for garnishing" .)