Shrub identified by the Italian divorcee (4)
I believe the answer is:
ilex
'shrub' is the definition.
(ilex is a genus of shrub)
'the italian divorcee' is the wordplay.
'the italian' becomes 'il' (the in Italian).
'divorcee' becomes 'ex' (I've seen this in other clues).
'il'+'ex'='ILEX'
'identified by' is the link.
(Other definitions for ilex that I've seen before include "The holly family of trees" , "'Tree group, includes holly (4)'" , "Tree of the genus that includes holly" , "Genus of trees that includes hollies" , "Holly, perhaps" .)