Swindle at seat of Irish kings? A harmless lie (10)
I believe the answer is:
taradiddle
'a harmless lie' is the definition.
'taradiddle' can be an answer for 'lie' (thesaurus). I am not certain of the 'a harmless' bit.
'swindle at seat of irish kings?' is the wordplay.
'swindle' becomes 'diddle' (synonyms).
'at' means one lot of letters go next to another (I've seen this in other clues).
'seat of irish kings?' becomes 'tara' (I've seen this in another clue).
'diddle' put after 'tara' is 'TARADIDDLE'.
Can you help me to learn more?
(Other definitions for taradiddle that I've seen before include "Nonsense" , "Tripe" , "Fiddlesticks!" .)