Allows to ripen (4)
I believe the answer is:
ages
'allows to ripen' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ages that I've seen before include "Matures" , "... of Man, according to WB Yeats" , "Times" , "Donkey's years" , "Historic periods or prolonged time" .)