The R in “country,” or “wrench” (6)
I believe the answer is:
sprain
'wrench' is the definition.
(sprain is a kind of wrench)
'the r in country' is the wordplay.
'in' means one lot of letters goes inside another.
'country' becomes 'spain' (Spain is an example).
'r' placed within 'spain' is 'SPRAIN'.
'or' acts as a link.
(Other definitions for sprain that I've seen before include "Pulled muscle" , "Injury to the ankle, say" , "Wrench a joint" , "Turn" , "Muscular injury caused by wrench" .)