Pick Rice mainly β very exciting! (8)
I believe the answer is:
electric
'exciting' is the definition.
(similar in meaning)
'pick rice mainly' is the wordplay.
'pick' becomes 'elect' (to elect is to pick or select).
'mainly' means to remove the last letter (virtually or mainly the word, but not all of it).
'rice' with its final letter removed is 'ric'.
'elect'+'ric'='ELECTRIC'
'very' is the link.
(Other definitions for electric that I've seen before include "Emotionally charged" , "Form of energy for lighting" , "This storm has lots of thunder and lightning" , "as fans may be?" , "Relating to a form of energy 98)" .)