Take no notice of developing region (6)
I believe the answer is:
ignore
'take no notice of' is the definition.
(to take no notice of something is to ignore it)
'developing region' is the wordplay.
'developing' indicates an anagram (letters developed into a new form).
'region' anagrammed gives 'IGNORE'.
(Other definitions for ignore that I've seen before include "Give no attention to" , "Fail to consider" , "Brush off" , "Disregard - cut" , "Slight" .)