I go in carelessly with valuable plant (13)
I believe the answer is:
bougainvillea
'plant' is the definition.
(bougainvillea matches up with the definition plant)
'i go in carelessly with valuable' is the wordplay.
'carelessly with' is an anagram indicator.
'i'+'go'+'in'='igoin'
'igoin' mixed up with 'valuable' can make 'BOUGAINVILLEA'.
(Other definitions for bougainvillea that I've seen before include "Ornamental tropical climber" , "Tropical woody climbing plant with red or purple bracts" , "Common climbing plant of the tropics" , "Woody climbing plant with conspicuous flower-heads" .)