Migrating heron is not far from the coast (7)
I believe the answer is:
inshore
'not far from the coast' is the definition.
(I've seen this before)
'migrating heron is' is the wordplay.
'migrating' is an anagram indicator (I've seen 'migrate' mean this).
'heron'+'is'='heronis'
'heronis' is an anagram of 'INSHORE'.
(Other definitions for inshore that I've seen before include "Close to the land" , "towards the coast from the sea" , "not far from the coast" , "coming in to land" , "close to beach" .)