Cheery lad, we hear (5)
I believe the answer is:
sunny
'cheery' is the definition.
(I know that cheery can be written as sunny)
'lad we hear' is the wordplay.
'lad' becomes 'sonny' (synonyms).
'we hear' shows a homophone (sound like).
'sonny' is a homophone of 'SUNNY'.
(Other definitions for sunny that I've seen before include "Cheerful; fine (weather)" , "Unclouded - cheerful" , "Bright and cheerful" , "Bright and warm" , "Genial, cheerful" .)