Know and see liar punished (7)
I believe the answer is:
realise
'know' is the definition.
('know'->'realize' is in my internal thesaurus and 'ize'->'ise')
'see liar punished' is the wordplay.
'punished' indicates anagramming the letters.
'see'+'liar'='seeliar'
'seeliar' with letters rearranged gives 'REALISE'.
'and' acts as a link.
(Other definitions for realise that I've seen before include "Twig" , "catch on" , "work out" , "appreciate" , "produce" .)