Vegetable mogul reaching the highest point (7)
I believe the answer is:
peaking
'reaching the highest point' is the definition.
'peaking' can be an answer for 'reaching' (peaking is a kind of reaching). I'm not sure about the 'the highest point' bit.
'vegetable mogul' is the wordplay.
'vegetable' becomes 'pea' (pea is a type of vegetable).
'mogul' becomes 'king' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'pea'+'king'='PEAKING'
Can you help me to learn more?
(Other definitions for peaking that I've seen before include "Reaching a high point" , "Reaching a maximum" .)