Chap of 50, nowadays? (3)
I believe the answer is:
lad
'chap' is the definition.
(I know that chap can be written as lad)
'50 nowadays?' is the wordplay.
'50' becomes 'l' (Roman numeral).
'nowadays?' becomes 'AD' (AD, Anno Domini, as opposed to BC, Before Christ).
'l'+'ad'='LAD'
'of' acts as a link.
(Other definitions for lad that I've seen before include "Stable employee" , "A young chap into ballads" , "Boy, young man" , "Boy or youth" , "Boy, familiar" .)