Cryptic crossword No 2,238

Across

1. Being first to investigate case of scam spearheaded by Johnson? (8)
2. A Republican male's shaft is where you're likely to encounter Musk (6)
3. Foreman? (4)
4. Supply clasp with diamonds and wool to cobblers (10)
5. Pointed digs made by American? (6)
6. One working out reasonably well? (8)
7. Beg creditor?! (7,6)
8. Smooth ruffled feathers and the rest! (4,4)
9. Picture one more thing you could have overlooked at first (6)
10. Relatively observant head of state? (3,7)
11. Those named here are put away (4)
12. Cooler subplot? (6)
13. Top Brexiteers backpedalling at first signs of economic and social turmoil (8)

Down

1. Uplifting passage uniting opposing sides? (6)
2. Holding to promote stock growth? (4)
3. Cautious individual escaped from trap (8)
4. One nibbling edges of leaf and crawling here and there? (6)
5. Illegally knocking out top student for politician without a word (10)
6. Stick-in-the-mud's using road improperly -- no good! (8)
7. Pig-headed centrist impeding progress along the way? (6,4,3)
8. To reach the desired position of Holy Father, one must be driven (10)
9. Blown pipe in cold toilet, water essentially hitting bottom (8)
10. Old priest mounting antique dealer (8)
11. Heard you indoors romping with sensational things picked up in Hooters (6)
12. Buffalo's on the plain (6)
13. Gillafox's forgotten end of the story (4)