Unusually gifted, initially schoolboy is restless (7)
I believe the answer is:
fidgets
'is restless' is the definition.
'unusually gifted initially schoolboy' is the wordplay.
'unusually' is an anagram indicator.
'initially' indicates taking the first letters.
The initial letter of 'schoolboy' is 's'.
'gifted' with letters rearranged gives 'fidget'.
'fidget'+'s'='FIDGETS'
(Other definitions for fidgets that I've seen before include "Restless folk" , "Displays restlessness" .)