Fronted about one and told porkies (4)
I believe the answer is:
lied
'told porkies' is the definition.
(I've seen this before)
'fronted about one' is the wordplay.
'fronted' becomes 'led' (I've seen this in another clue).
'about' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'led' enclosing 'i' is 'LIED'.
'and' acts as a link.
(Other definitions for lied that I've seen before include "refused to admit it" , "piece of music" , "Song in Berlin" , "Did not speak the truth" , "gave a false impression" .)