The club for many a cross-country runner (6)
I believe the answer is:
driver
'the club' is the definition.
(type of golf club)
'many a cross-country runner' is the wordplay.
I cannot quite understand how this works, but
'many' could be 'd' (Roman numeral for 500) and 'd' is located in the answer.
'runner' could be 'river' and 'river' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'for' is the link.
Can you help me to learn more?
(Other definitions for driver that I've seen before include "Flat-faced golf club" , "Operator of a motor vehicle" , "chauffeuse" , "Golf club for long shots" , "Golf-club for a motorist" .)