Ambassador frequently flanked by two chaps who launched ships? (5,2,4)
I believe the answer is:
helen of troy
'flanked by two chaps who launched ships?' is the definition.
I don't know anything about this answer so I can't tell whether this works.
'ambassador frequently' is the wordplay.
I cannot really see how this works, but
'ambassador' could be 'he' (His or Her Excellency) and 'he' is located in the answer.
'frequently' could be 'oft' (I've seen this before) and 'oft' is found within the answer.
This may be the basis of clue (or it may be nonsense).
(Other definitions for helen of troy that I've seen before include "Femme fatale" , "Her face "launched a thousand ships"" , "She went to Paris" , "Famous beauty" , "She was abducted by Paris, starting a war" .)