Manufacturer right below form (5)
I believe the answer is:
maker
'manufacturer' is the definition.
(I know that manufacturer can be written as maker)
'right below form' is the wordplay.
'right' becomes 'r' (abbreviation).
'below' says to put letters next to each other (in a down clue, some letters go below others).
'form' becomes 'make' (synonyms).
'r' put after 'make' is 'MAKER'.
(Other definitions for maker that I've seen before include "Producer" , "Fabricator; poet (arch.)" , "One who creates or constructs" , "Creator" , "God Almighty" .)