Showing ambition in the form of sanctimonious tirade (8)
I believe the answer is:
aspirant
'showing ambition' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'form of sanctimonious tirade' is the wordplay.
'form of' becomes 'as' (I can't explain this - if you can you should believe this answer much more).
'sanctimonious' becomes 'pi' (British abbreviation for pious).
'tirade' becomes 'rant' (both can mean an angry outburst).
'as'+'pi'+'rant'='ASPIRANT'
'in the' acts as a link.
Can you help me to learn more?
(Other definitions for aspirant that I've seen before include "Would-be" , "Partisan may be person with high ambition" , "Partisan (anag)" , "One with ambition" , "One works hard to achieve something" .)