Fail to appreciate development of region (6)
I believe the answer is:
ignore
'fail to appreciate' is the definition.
(to fail to appreciate or understand)
'development of region' is the wordplay.
'development of' is an anagram indicator (I've seen 'development' mean this).
'region' with letters rearranged gives 'IGNORE'.
(Other definitions for ignore that I've seen before include "Pass over" , "Pay no attention to, disdain" , "Turn a blind eye to" , "Fail to notice (6)" , "bypass" .)