Country roads run up underneath a weapons store (7)
I believe the answer is:
arsenal
'weapons store' is the definition.
(I've seen this before)
'country roads run up underneath a' is the wordplay.
'country roads' becomes 'lanes' (I've seen this before).
'run' becomes 'r' (cricket abbreviation).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'underneath' says to put letters next to each other (I've seen this in other clues).
'lanes'+'r'='lanesr'
'lanesr' back-to-front is 'rsenal'.
'rsenal' after 'a' is 'ARSENAL'.
(Other definitions for arsenal that I've seen before include "Munitions store and English football team" , "Store of weaponry" , "London premiership football team" , "Collection of weapons" , "Military structure for arms and ammunitions" .)