First in earlier on? Social worker, smart (7)
I believe the answer is:
elegant
'smart' is the definition.
('elegant' can be similar in meaning to 'smart')
'first in earlier on? social worker' is the wordplay.
'first in' indicates taking the first letters.
'on?' becomes 'leg' (cricket term, fielding positions).
'social worker' becomes 'ant' (I've seen this before).
The initial letter of 'earlier' is 'e'.
'e'+'leg'+'ant'='ELEGANT'
(Other definitions for elegant that I've seen before include "Refined and dignified in appearance" , "Gracefully stylish" , "Refined gracefulness" , "Polished" , "Ingenious" .)