Work ethics to welcome mathematical chief boffin (7)
I believe the answer is:
chemist
'boffin' is the definition.
(boffin can mean a scientist)
'work ethics to welcome mathematical chief' is the wordplay.
'work' indicates an anagram.
'to welcome' is an insertion indicator (in sense of 'inviting in').
'chief' says to take the initial letters.
The first letter of 'mathematical' is 'm'.
'ethics' anagrammed gives 'cheist'.
'cheist' going around 'm' is 'CHEMIST'.
(Other definitions for chemist that I've seen before include "Seller of medications" , "Seller of medicines and toiletries" , "Drugs/toiletries shop" , "Medicine dispenser" , "Nobel, say" .)