Waylay a muddle-headed old president (6)
I believe the answer is:
ambush
'waylay' is the definition.
(synonyms)
'a muddle-headed old president' is the wordplay.
'a muddle-headed old' becomes 'am' (I can't justify this - if you can you should believe this answer much more).
'president' becomes 'Bush' (two US presidents have been called Bush).
'am'+'bush'='AMBUSH'
Can you help me to learn more?
(Other definitions for ambush that I've seen before include "Wait in hiding to attack" , "Waylaying" , "raid" , "Lie in wait and attack" , "Lying in wait to attack" .)