Crossword Genius

One who is this still needs a crash helmet, being unsentimental (10)

Ross

I believe the answer is:

hardheaded

'unsentimental' is the definition.
(thesaurus)

I don't understand the rest of the clue.

(Another definition for hardheaded that I've seen is " Tough".)

I've seen this clue in The Times.
Want a hint initially instead of a full solution? Install my app