Beetle: boy gets rid by shaking (8)
I believe the answer is:
ladybird
'beetle' is the definition.
(ladybird beetle is a kind of beetle)
'boy gets rid by shaking' is the wordplay.
'boy' becomes 'lad' (lad is a kind of boy**).
'gets' means one lot of letters goes inside another (gets can mean captures or absorbs).
'shaking' indicates anagramming the letters.
'rid'+'by'='ridby'
'ridby' is an anagram of 'dybir'.
'lad' enclosing 'dybir' is 'LADYBIRD'.
(Other definitions for ladybird that I've seen before include "This insect likes greenfly" , "Red insect with black spots" , "Beetle spotted by black" , "spotted one that flies" , "Common insect" .)