Deer location, reported in retrospect (9)
I believe the answer is:
hindsight
'retrospect' is the definition.
(thesaurus)
'deer location reported' is the wordplay.
'deer' becomes 'hind' (hind is a kind of deer).
'location' becomes 'site' (site is a kind of location).
'reported' shows a homophone (sound like).
'site' is a homophone of 'sight'.
'hind'+'sight'='HINDSIGHT'
'in' is the link.
(Other definitions for hindsight that I've seen before include "Thinking back" , "Ability to understand, perhaps too late" , "Wisdom after the event" , "Looking back" , "review" .)