Sounding sanctimonious in head to head (7,4)
I believe the answer is:
opinion poll
'sounding' is the definition.
(I've seen this before)
'sanctimonious in head to head' is the wordplay.
I cannot quite see how this works, but
'sanctimonious' could be 'pi' (British abbreviation for pious) and 'pi' is present in the answer.
'head' could be 'onion' (informal term for someone's head or brain) and 'onion' is located in the remaining letters.
'to head' could be 'poll' (poll is a now rare word for head or scalp) and 'poll' is located in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for opinion poll that I've seen before include "Sounding" , "Survey of public views" , "Test of voting intention" , "Test of voting intentions" .)