Mark to enquire about performing rites (8)
I believe the answer is:
asterisk
'mark' is the definition.
(asterisking is a kind of marking)
'enquire about performing rites' is the wordplay.
'enquire' becomes 'ask' (to enquire is to ask or question).
'about' means one lot of letters goes inside another.
'performing' indicates anagramming the letters (the letters move around or 'perform').
'rites' with letters rearranged gives 'teris'.
'ask' placed around 'teris' is 'ASTERISK'.
'to' acts as a link.
(Other definitions for asterisk that I've seen before include "Text-marking symbol" , "Printed star" , "Star-like symbol as reference mark" , "Star-shape on the page" , "Printer's star" .)