Promise of spring before end of June? (4)
I believe the answer is:
hope
'promise' is the definition.
('hope' can be a synonym of 'promise')
'spring before end of june?' is the wordplay.
'spring' becomes 'hop' (I've seen this before**).
'before' is a charade indicator (letters next to each other).
'end of' says to take the final letters.
The last letter of 'june' is 'e'.
'hop'+'e'='HOPE'
'of' is the link.
(Other definitions for hope that I've seen before include "Anticipation" , "Cherish a desire" , "'. . . . springs eternal in the human breast'" , "Expect and desire" , "Aspiration" .)