Put off, having left one flower (5)
I believe the answer is:
tulip
'flower' is the definition.
(tulip is a type of flower)
'put off having left one' is the wordplay.
'off' indicates an anagram.
'having' is an insertion indicator.
'left' becomes 'l' (common abbreviation).
'one' becomes 'i' (Roman numeral).
'put' is an anagram of 'tup'.
'l'+'i'='li'
'tup' going around 'li' is 'TULIP'.
(Other definitions for tulip that I've seen before include "Amsterdam bloom?" , "Flower - lit up (anag)" , "cause of mania once" , "Liliaceous plant with a spring flower" , "Dutch export" .)