Speedy car repair service in block south of mine (3,4)
I believe the answer is:
pit stop
'speedy car repair service' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'block south of mine' is the wordplay.
'block' becomes 'stop' (synonyms).
'south of' means one lot of letters go next to another (in a down clue, some letters go under others).
'mine' becomes 'pit' (down the pit).
'stop' after 'pit' is 'PIT STOP'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for pit stop that I've seen before include "for rest of travellers" , "period of service?" , "Break for fuel etc." , "brief service" , "When tripping, break" .)