Turkey perhaps following mongrel -- run! (5-7)
I believe the answer is:
cross-country
'turkey perhaps following mongrel run' is the definition.
I can't tell whether this defines the answer.
'turkey perhaps following mongrel' is the wordplay.
'turkey perhaps' becomes 'country' (turkey is a kind of country).
'following' is a charade indicator (letters next to each other).
'mongrel' becomes 'cross' (cross breed).
'country' put after 'cross' is 'CROSS-COUNTRY'.
Can you help me to learn more?
(Other definitions for cross-country that I've seen before include "Running sport" , "Rural running event" .)