Plant: unusual bush about right? (5)
I believe the answer is:
shrub
'plant' is the definition.
(shrub is a kind of plant)
'unusual bush about right?' is the wordplay.
'unusual' is an anagram indicator.
'about' is an insertion indicator.
'right?' becomes 'r' (common abbreviation).
'bush' is an anagram of 'shub'.
'shub' enclosing 'r' is 'SHRUB'.
(Other definitions for shrub that I've seen before include "Hazel perhaps" , "Low woody perennial type of plant" , "Perhaps Heather" , "Plant - brush (anag)" , "Mixed drink of rum, sugar, fruit-juice and spice" .)