Ambassador wantonly told PM a naked fib (8)
I believe the answer is:
diplomat
'ambassador' is the definition.
(I've seen this before)
'wantonly told pm a naked fib' is the wordplay.
'wantonly' indicates an anagram (I've seen this in other clues).
'naked' indicates the central letters (outside letters removed so centre is unclothed).
The central letter of 'fib' is 'i'.
'told'+'pm'+'a'+'i'='toldpmai'
'toldpmai' is an anagram of 'DIPLOMAT'.
(Other definitions for diplomat that I've seen before include "envoy, say" , "Limp toad (anag.)" , "tactful one" , "One who represents his govermnent abroad" , "Official such as an ambassador" .)