French biologist beyond regret when back-tracking (7)
I believe the answer is:
pasteur
'french biologist' is the definition.
'Pasteur' can be an answer for 'biologist' (Pasteur is an example). I am not sure about the 'french' bit.
'beyond regret when back-tracking' is the wordplay.
'beyond' becomes 'past' (to go beyond something is to go past it).
'regret when' becomes 'rue' (to rue something is to regret it. I am not sure about the 'when' bit.).
'back-tracking' shows that the letters should be reversed in order.
'rue' back-to-front is 'eur'.
'past'+'eur'='PASTEUR'
Can you help me to learn more?
(Other definitions for pasteur that I've seen before include "Louis --, French chemist/bacteriologist" , "He invented a method to stop milk causing disease" , "Louis --, French bacteriologist" , "French chemist and biologist (1822-1895)" , "Pioneer immunologist" .)