Erica and he having a change of heart (7)
I believe the answer is:
heather
'erica' is the definition.
(plant genus including heather)
'he having a change of heart' is the wordplay.
'having' means one lot of letters go next to another.
'a change of' indicates anagramming the letters (the letter order is changed).
'heart' is an anagram of 'ather'.
'he'+'ather'='HEATHER'
'and' acts as a link.
(Other definitions for heather that I've seen before include "Evergreen shrub" , "Plant also called ling" , "thing seen on the moors" , "Moorland plant" , "grows wild" .)