Appearing embarrassed in company revealing set of beliefs (5)
I believe the answer is:
credo
'set of beliefs' is the definition.
(I've seen this before)
'appearing embarrassed in company' is the wordplay.
'appearing embarrassed' becomes 'red'.
'in' means one lot of letters goes inside another.
'company' becomes 'co' (abbreviation).
'red' placed within 'co' is 'CREDO'.
'revealing' acts as a link.
(Other definitions for credo that I've seen before include "Part of the service" , "Formal statement of principles" , "I believe in Latin" , "Statement of guiding aims" , "music in church" .)