Old browser I rejected as you are texting way ahead (9)
I believe the answer is:
stegosaur
'old browser' is the definition.
(extinct browsing animal)
'i rejected as you are texting way ahead' is the wordplay.
'i' becomes 'ego' ('I' in Latin).
'rejected as' becomes 'sa' (I can't explain this - if you can you should give a lot more credence to this answer).
'you are texting' becomes 'ur' (abbreviation for 'you are' when texting).
'way' becomes 'st' (abbreviation for street).
'ahead' means one lot of letters go next to another (some letters go in front of others).
'ego'+'sa'+'ur'='egosaur'
'egosaur' after 'st' is 'STEGOSAUR'.
(Other definitions for stegosaur that I've seen before include "prehistoric creature" , "Old veggie" , "old dinosaur" , "Jurassic creature" , "Old beast" .)