Avoid awful heap that is deformed (8)
I believe the answer is:
misshape
'that is deformed' is the definition.
(misshape can mean a misshapen or deformed thing)
'avoid awful heap' is the wordplay.
'avoid' becomes 'miss' (miss can mean to avoid).
'awful' is an anagram indicator.
'heap' with letters rearranged gives 'hape'.
'miss'+'hape'='MISSHAPE'
(Other definitions for misshape that I've seen before include "bad figure" , "Distort" , "disfigurement" , "Fashion poorly" , "How football appears to a rugby player" .)