Private selection of perennials picked up (5)
I believe the answer is:
inner
'private' is the definition.
(as in one's private or inner thoughts)
'selection of perennials picked up' is the wordplay.
'selection of' says the answer is hidden in the clue.
'picked up' says the letters should be written in reverse.
'renni' can be found hidden inside 'perennials'.
'renni' back-to-front is 'INNER'.
(Other definitions for inner that I've seen before include "Located or occurring closer to a centre" , "Opposite of outer" , "Ring round the target bull." , "It's next to the bull on the board" , "Interior" .)