Lass of frugality (3)
I believe the answer is:
gal
'lass' is the definition.
(I've seen this before)
'of frugality' is the wordplay.
'of' indicates a hidden word.
'GAL' is hidden within 'frugality'.
(Other definitions for gal that I've seen before include "female noted in Kalamazoo" , "miss" , "Girl from American west" , "Lady" , "Lass" .)