Waylay old US president on eastern half of Pacific island (6)
I believe the answer is:
ambush
'waylay old' is the definition.
'ambush' can be an answer for 'waylay' (synonyms). I'm not certain of the 'old' bit.
'us president on eastern half of pacific island' is the wordplay.
'us president' becomes 'bush' (George H W Bush or George W Bush).
'on' is a charade indicator (letters next to each other).
'eastern' shows that the letters should be reversed in order (letters written right to left or east to west).
'half of pacific island' becomes 'ma' (I am not sure about this - if you are sure you should believe this answer much more).
'ma' written backwards gives 'am'.
'bush' after 'am' is 'AMBUSH'.
Can you help me to learn more?
(Other definitions for ambush that I've seen before include "Attack from concealed position" , "Wait in hiding to attack" , "Launch attack from hiding" , "Jump" , "Waylaying" .)