Lied about Conservative promises being tasteful (9)
I believe the answer is:
delicious
'tasteful' is the definition.
(similar in meaning)
'lied about conservative promises' is the wordplay.
'about' indicates an anagram.
'conservative' becomes 'C' (UK political abbreviation).
'promises' becomes 'IOUs' (promises to pay a debt).
'lied' is an anagram of 'deli'.
'deli'+'c'+'ious'='DELICIOUS'
'being' acts as a link.
(Other definitions for delicious that I've seen before include "Pleasant tasting" , "Delightful; tasty" , "very nice" , "Very pleasant to taste" , "Yummy" .)