Swore to delete text about Frenchman on island (8)
I believe the answer is:
promised
'swore' is the definition.
(I've seen this before)
'delete text about frenchman on island' is the wordplay.
'delete text' becomes 'prosed' (I can't explain this - if you can you should believe this answer much more).
'about' indicates putting letters inside.
'frenchman' becomes 'm' (abbreviation for Monsieur - like 'Mr').
'on' means one lot of letters go next to another.
'island' becomes 'i' (geographical abbreviation).
'm'+'i'='mi'
'prosed' placed around 'mi' is 'PROMISED'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for promised that I've seen before include "swore" , "Undertook (to do something)" , "undertaken" , "Made a commitment to do" , "Betrothed" .)