Hunt for a long time (6)
I believe the answer is:
forage
'hunt' is the definition.
(foraging is a kind of hunting)
'for a long time' is the wordplay.
'a long time' becomes 'age' (an age is a period of time).
'for'+'age'='FORAGE'
(Other definitions for forage that I've seen before include "Hunt for food or provisions" , "Seek for food" , "Search around for food" , "Rummage, search for" , "Search widely for food" .)