It is suggested that one member was untruthful (7)
I believe the answer is:
implied
'it is suggested' is the definition.
(implying is a kind of suggesting)
'one member was untruthful' is the wordplay.
'one' becomes 'i' (Roman numeral).
'member' becomes 'MP' (Member of Parliament).
'was untruthful' becomes 'lied' (I've seen this in another clue).
'i'+'mp'+'lied'='IMPLIED'
'that' is the link.
(Other definitions for implied that I've seen before include "Unspoken" , "Tacit" , "State indirectly" , "Suggested without stating directly" , "Suggested; not explicit" .)