Well before summer (6)
I believe the answer is:
spring
This clue is a double definition.
'well' is the first definition.
(a well is a spring of water)
'before summer' is the second definition.
(Other definitions for spring that I've seen before include "Vivaldi's work, in order(6;6;6;6)" , "Well - bound" , "See 11" , "Bound < to start" , "new dawn?" .)