Picture pretty as could be (8)
I believe the answer is:
tapestry
'picture' is the definition.
(I've seen this before)
'pretty as could be' is the wordplay.
'could be' indicates anagramming the letters.
'pretty'+'as'='prettyas'
'prettyas' is an anagram of 'TAPESTRY'.
(Other definitions for tapestry that I've seen before include "Woven or embroidered textile" , "a picture on the wall" , "Complexity" , "Fabric picture" , "Decorative hanging" .)