Copy OK intern to become person limited to a single talent, say (3-5,4)
I believe the answer is:
one-trick pony
'person limited to a single talent say' is the definition.
I can't judge whether this defines the answer.
'copy ok intern to become' is the wordplay.
'to become' is an anagram indicator.
'copy'+'ok'+'intern'='copyokintern'
'copyokintern' is an anagram of 'ONE-TRICK PONY'.
Can you help me to learn more?
(Other definitions for one-trick pony that I've seen before include "Person (or animal) with a limited repertoire - krypton on ice (anag)" , "Person noteworthy only for a single skill" .)