Cheerful lad reportedly associated with worker (7)
I believe the answer is:
buoyant
'cheerful' is the definition.
(I've seen this before)
'lad reportedly associated with worker' is the wordplay.
'lad' becomes 'boy' (I've seen this before).
'reportedly' shows a homophone (sound like).
'associated with' says to put letters next to each other.
'worker' becomes 'ant' (worker is a type of ant).
'boy' sounds like 'buoy'.
'buoy'+'ant'='BUOYANT'
(Other definitions for buoyant that I've seen before include "light-hearted" , "Bouncy" , "Cheerful, optimistic" , "In good spirits" , "Able to float" .)