Cryptic crossword No 3,889

Across

1. Alkaline substance came into contact with something below ground (8)
2. Take most of medicine with a little hesitation (6)
3. Goodwood? (4)
4. Permit drunk cops for example to get into the club (10)
5. Flicks buff folder which has nothing in it by head of research (8)
6. Article on the front of Sunday paper (6)
7. Hold on to small house in East London? (6)
8. Declining to take part in parade, end entertainment (10)
9. Parasite found in chipmunk's skin (4)
10. Brought back first gas services over nine days (6)
11. Showed picture frame to Steve which has need for repair (8)
12. Driver takes this strategic nap, according to Spooner (9,4)
13. Carrier put copper back in wrong racks (8)

Down

1. Put up shed (6)
2. Put out red carpet regularly, we trust, for old buggers (4,9)
3. Prepared antipasti, but not finished with ingredient used in dips (6)
4. Unwrapped free present (4)
5. Man left landing area (8)
6. Those who make bloomers and who wash them without a... (10)
7. ...break, initially repairing inseam and taking hem in (8)
8. Source of income from Middle East with deferred payment terms supported by Egypt (4,6)
9. Feature award of medal in play written by soldiers (5,3)
10. Gesture with baton could be indication to Territorial Army? (6)
11. Journalist getting lashed (4)
12. Prestige in Switzerland and in France (6)
13. Those establishing bearings of mountain pass running back over a peak (8)