Amazingly great time for goal (6)
I believe the answer is:
target
'for goal' is the definition.
(target is a kind of goal)
'amazingly great time' is the wordplay.
'amazingly' indicates anagramming the letters.
'time' becomes 't' (abbreviation).
'great' is an anagram of 'targe'.
'targe'+'t'='TARGET'
(Other definitions for target that I've seen before include "Aimpoint" , "Reference point to shoot at" , "Point to aim at (6)." , "Thing to aim at" , "Goal; victim" .)