Pungent scrap turned over tongue unknown (8)
I believe the answer is:
garlicky
'pungent' is the definition.
(similar in meaning)
'scrap turned over tongue unknown' is the wordplay.
'scrap' becomes 'rag' (I've seen this before).
'turned over' says the letters should be written in reverse.
'tongue' becomes 'lick'.
'unknown' becomes 'y' (algebra).
'rag' back-to-front is 'gar'.
'gar'+'lick'+'y'='GARLICKY'
(Other definitions for garlicky that I've seen before include "Likely to cause bad breath when eaten?" , "Strong-smelling" , "tasting of cloves?" , "somewhat pungent" .)