In spring, is allowed to (3)
I believe the answer is:
may
I believe this clue is a double definition.
'in spring' is the first definition.
('May' is part of 'spring')
'is allowed to' is the second definition.
(may I?)
(Other definitions for may that I've seen before include "Has permission" , "The merry merry month( 3)" , "Could" , "Girl's name; 10 ac (anag.)" , "Hawthorm blossom" .)