Repeated chant of chap heading for trapeze artist (6)
I believe the answer is:
mantra
'repeated chant' is the definition.
(a repeated slogan or phrase)
'chap heading for trapeze artist' is the wordplay.
'chap' becomes 'man' (chap can mean a man).
'heading for' says to take the initial letters.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
The initial letter of 'trapeze' is 't'.
'man'+'t'+'ra'='MANTRA'
'of' acts as a link.
(Other definitions for mantra that I've seen before include "Word or phrase repeated as aid to concentration" , "Buddhist chant" , "Repeated incantation" , "Several words repeated frequently" , "Sacred text used as incantation" .)