Rich fools about to accept dodgy myth on a regular basis (8)
I believe the answer is:
rhythmic
'on a regular basis' is the definition.
(with a regular rhythm)
'rich fools about to accept dodgy myth' is the wordplay.
'fools about' is an anagram indicator.
'to accept' means one lot of letters goes inside another.
'dodgy' is an anagram indicator (a dodgy or wrong order of the letters).
'rich' with letters rearranged gives 'rhic'.
'myth' is an anagram of 'ythm'.
'rhic' placed around 'ythm' is 'RHYTHMIC'.
(Other definitions for rhythmic that I've seen before include "Measured, metrical" , "With a strong sound pattern" , "Rich myth strangely recurs at regular intervals" , "Having strong or regular beat as in music" , "Throbbing" .)