Hunter blowing top about a time limit (6)
I believe the answer is:
ration
'limit' is the definition.
(rationing is a kind of limiting)
'hunter blowing top about a time' is the wordplay.
'hunter' becomes 'orion' (constellation).
'blowing top' means to remove the first letter.
'about' means one lot of letters goes inside another.
'time' becomes 't'.
'orion' with its first letter removed is 'rion'.
'a'+'t'='at'
'rion' placed around 'at' is 'RATION'.
(Other definitions for ration that I've seen before include "Food apportionment" , "Dole out in measured quantities, as in time of shortage" , "Limited allocation of food etc in wartime" , "Eke out" , "Fixed share" .)