I'm after new top first, being a cheerful type (8)
I believe the answer is:
optimist
'a cheerful type' is the definition.
(I've seen this before)
'i'm after new top first' is the wordplay.
'after' says to put letters next to each other.
'new' indicates an anagram.
'first' becomes 'ist' ().
'top' anagrammed gives 'opt'.
'im' after 'opt' is 'optim'.
'optim'+'ist'='OPTIMIST'
'being' is the link.
(Other definitions for optimist that I've seen before include "Panglossian type" , "One wearing rose-tinted spectacles" , "Person who always looks on the bright side" , "One looking on bright side" , "cheerful type" .)