After month, head off with artist, making shapes (9)
I believe the answer is:
octahedra
'shapes' is the definition.
(octahedron is a kind of shape)
'after month head off with artist' is the wordplay.
'after' means one lot of letters go next to another.
'month' becomes 'oct' (abbreviation for October).
'off' is an anagram indicator.
'with' says to put letters next to each other.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'head' anagrammed gives 'ahed'.
'oct'+'ahed' is 'octahed'.
'octahed'+'ra'='OCTAHEDRA'
'making' is the link.
(Other definitions for octahedra that I've seen before include "shapes" , "solids" , "Solid figures with eight plane faces" , "Eight-sided figures" , "Solid artefacts" .)