Formula One is in Monaco on a holiday (6)
I believe the answer is:
fiesta
'holiday' is the definition.
(I've seen this in another clue)
'formula one is in monaco on a' is the wordplay.
'formula one' becomes 'FI' (resembles Fe).
'is in monaco' becomes 'est' (I can't justify this - if you can you should believe this answer much more).
'on' means one lot of letters go next to another.
'fi'+'est'+'a'='FIESTA'
Can you help me to learn more?
(Other definitions for fiesta that I've seen before include "(Iberian) religious holiday" , "A Spanish public celebration" , "A public holiday in Barcelona" , "Public whoopee in Spain" , "Religious festival in Hispanic communities" .)