Trio taken short in country road, finding loo (7)
I believe the answer is:
latrine
'loo' is the definition.
(I know that latrine is a type of loo)
'trio taken short in country road' is the wordplay.
'taken short' means to remove the last letter.
'in' is an insertion indicator.
'country road' becomes 'lane' (I've seen this in another clue).
'trio' with its last letter taken off is 'tri'.
'tri' placed within 'lane' is 'LATRINE'.
'finding' is the link.
(Other definitions for latrine that I've seen before include "Camp lavatory" , "An army loo" , "Lavatory (in barracks)" , "Primitive toilet" , "Army lavatory" .)