Bulb will start to open before end of August (7)
I believe the answer is:
shallot
'bulb' is the definition.
(shallot is a kind of bulb)
'will start to open before end of august' is the wordplay.
'will' becomes 'shall' ('shall' can be a synonym of 'will'**).
'start to' says to take the initial letters.
'before' is a charade indicator (letters next to each other).
'end of' says to take the final letters.
The first letter of 'open' is 'o'.
The last letter of 'august' is 't'.
'shall'+'o'+'t'='SHALLOT'
(Other definitions for shallot that I've seen before include "One may get into a stew" , "found in the allotment" , "Scallion" , "Rowing boat" , "bit of salad" .)