Tiny bit of wet weather after end of spring (5)
I believe the answer is:
grain
'tiny bit' is the definition.
(I've seen this in another clue)
'wet weather after end of spring' is the wordplay.
'wet weather' becomes 'rain' (rain is wet weather).
'after' means one lot of letters go next to another.
'end of' suggests the final letters.
The final letter of 'spring' is 'g'.
'rain' put after 'g' is 'GRAIN'.
'of' acts as a link.
(Other definitions for grain that I've seen before include "Cereal crops" , "Small hard seed of corn etc" , "Structure of wood" , "bit of corn" , "Character" .)