Helped a seed to burst (5)
I believe the answer is:
eased
'helped' is the definition.
(easing is a kind of helping)
'a seed to burst' is the wordplay.
'to burst' indicates an anagram.
'a'+'seed'='aseed'
'aseed' is an anagram of 'EASED'.
(Other definitions for eased that I've seen before include "Oiled" , "Abated" , "Lessened, pain or discomfort, say" , "Made less difficult, relieved from anxiety" , "Released pressure" .)