Put up with having left one bloomer (5)
I believe the answer is:
tulip
'bloomer' is the definition.
(I've seen this before)
'put up with having left one' is the wordplay.
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'with having' indicates putting letters inside.
'left' becomes 'l' (common abbreviation).
'one' becomes 'i' (Roman numeral).
'put' in reverse letter order is 'tup'.
'l'+'i'='li'
'tup' placed around 'li' is 'TULIP'.
(Other definitions for tulip that I've seen before include "Garden flower from bulb" , "Spring-blooming plant" , "(Dutch) bloom" , "Amsterdam bloom?" , ""Dutch" flower" .)