Lord Ted trained a two-year-old (7)
I believe the answer is:
toddler
'a two-year-old' is the definition.
'lord ted trained' is the wordplay.
'trained' is an anagram indicator (to train can mean to grow something into a shape).
'lord'+'ted'='lordted'
'lordted' anagrammed gives 'TODDLER'.
(Other definitions for toddler that I've seen before include "Child starting to walk" , "Child just learning to walk" , "Young walker" , "Lord Ted (anag)" , "Young child" .)