Offer to purchase artist's twisted material (5)
I believe the answer is:
braid
'twisted material' is the definition.
'offer to purchase artist's' is the wordplay.
'offer' becomes 'bid' (bid is a kind of offer).
'to purchase' is an insertion indicator.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'bid' going around 'ra' is 'BRAID'.
(Other definitions for braid that I've seen before include "Plaited length, of hair say." , "Ornamental strip" , "decoration" , "Hairdo formed by twisting the hair" , "As before, reproach" .)