Meaning of one politician being 'economical with the truth' (8)
I believe the answer is:
implying
'meaning' is the definition.
('imply' can be a synonym of 'mean')
'one politician being economical with the truth' is the wordplay.
'one' becomes 'i' (Roman numeral).
'politician' becomes 'MP' (Member of Parliament).
'being economical with the truth' becomes 'lying' (being economical with truth means lying).
'i'+'mp'+'lying'='IMPLYING'
'of' acts as a link.
(Other definitions for implying that I've seen before include "Meaning" , "Indicating by suggestion" , "Insinuating; signifying" , "making insinuations" , "Suggesting" .)