Notice a change in plant (7)
I believe the answer is:
aconite
'in plant' is the definition.
'aconite' can be an answer for 'plant' (I've seen this before). I am not certain of the 'in' bit.
'notice a change' is the wordplay.
'change' is an anagram indicator.
'notice'+'a'='noticea'
'noticea' is an anagram of 'ACONITE'.
Can you help me to learn more?
(Other definitions for aconite that I've seen before include "Flower, for example monkshood or wolfsbane" , "potential killer" , "Poisonous flowering plant" , "Spring flower - poison" , "Yellow-flowered plant" .)