Relish: some giving us toothache (5)
I believe the answer is:
gusto
'relish' is the definition.
('gusto' can be a synonym of 'relish')
'some giving us toothache' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'GUSTO' can be found hidden inside 'giving us toothache'.
(Other definitions for gusto that I've seen before include "Relish - zest" , "Got us with great enjoyment" , "Great relish" , "Spirit" , "Great enthusiasm" .)