Youngsters writing about wrought iron (6)
I believe the answer is:
minors
'youngsters' is the definition.
('minor' can be a synonym of 'youngster')
'writing about wrought iron' is the wordplay.
'writing' becomes 'ms' (abbreviation for manuscript).
'about' indicates putting letters inside.
'wrought' is an anagram indicator (wrought means beaten into a new shape).
'iron' with letters rearranged gives 'inor'.
'ms' enclosing 'inor' is 'MINORS'.
(Other definitions for minors that I've seen before include "They're under-age" , "could be little ones" , "They're too young to vote" , "They are legally under-age" , "Young people" .)