Place where "posh” has replaced a mode of speech (8)
I believe the answer is:
locution
'speech' is the definition.
(I know that locution is a type of speech)
'place where posh has replaced a mode of' is the wordplay.
I cannot quite see how this works, but
'posh' could be 'u' (abbreviation for upper-class - opposite to non-U) and 'u' is found within the answer.
'mode' could be 't' and 't' is located in the answer.
'of' could be 'o' and 'o' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for locution that I've seen before include "Mode of expression" , "Style of speech or idiom" , "way of speaking" , "utterance" , "Person's style of speech" .)