Flower, small at this time, ahead of fall (8)
I believe the answer is:
snowdrop
'flower' is the definition.
(snowdrop is a kind of flower)
'small at this time ahead of fall' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'at this time' becomes 'now' (I've seen this before).
'ahead of' means one lot of letters go next to another (I've seen this in other clues).
'fall' becomes 'drop' (dropping is a kind of falling).
's'+'now'+'drop'='SNOWDROP'
(Other definitions for snowdrop that I've seen before include "Wood anemone" , "Avalanche perhaps" , "A blooming" , "White-flowered plant (Galanthus nivalis)" , "Plant with drooping white flowers" .)