Press hack finds old railway engine (4,5)
I believe the answer is:
iron horse
'old railway engine' is the definition.
'iron horse' can be an answer for 'engine' (iron horse is a kind of engine). I'm not certain of the 'old railway' bit.
'press hack' is the wordplay.
'press' becomes 'iron' (ironing is a kind of pressing).
'hack' becomes 'horse' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'iron'+'horse'='IRON HORSE'
'finds' acts as a link.
Can you help me to learn more?
(Other definitions for iron horse that I've seen before include "worn-out engine" , "Steam locomotive" , "Train leader" , "one's gone off the rails" , "film once in America!" .)