Hard sell that executives initially see (6)
I believe the answer is:
steely
'hard' is the definition.
(similar in meaning)
'sell that executives initially see' is the wordplay.
'initially' indicates taking the first letters.
'see' becomes 'ely' (see is a place with a cathedral - e.g. Ely).
The initial letters of 'sell that executives' is 'ste'.
'ste'+'ely'='STEELY'
(Other definitions for steely that I've seen before include "As hard, or grey, as metal" , "Gimlet-eyed" , "Obdurate" , "Inflexibly severe" , "With (cold) resolve" .)