Pictures left by artist having oddly deficient vistas (9)
I believe the answer is:
portraits
'pictures' is the definition.
(portrait is a kind of picture)
'left by artist having oddly deficient vistas' is the wordplay.
'left' becomes 'port' (left side of a ship - opposite of starboard).
'by' says to put letters next to each other.
'artist' becomes 'ra' (Royal Academician, member of Royal Academy of Arts).
'having' says to put letters next to each other.
'oddly deficient' means one should take alternating letters (letters in odd-numbered positions removed).
The alternating letters of 'vistas' are 'its'.
'port'+'ra'+'its'='PORTRAITS'
(Another definition for portraits that I've seen is " Paintings".)