Sanctimonious bunch making TV try-out (5)
I believe the answer is:
pilot
'tv try-out' is the definition.
(trial episode of a TV show)
'sanctimonious bunch' is the wordplay.
'sanctimonious' becomes 'pi' (British abbreviation for pious).
'bunch' becomes 'lot' (synonyms).
'pi'+'lot'='PILOT'
'making' is the link.
(Other definitions for pilot that I've seen before include "Aviator" , "Guide, leader" , "He steers ship or plane" , "Small flame that ignites a gas boiler" , "Name of Mr Rochester's dog" .)