Cryptic crossword No 3,685

Across

1. Clasp a bust? It's a French polymath! (6)
2. Old motorcylce test reportedly unsuccessful initially at speed. (7)
3. Chart covering a Federal district is crazy (6)
4. Study of shape-changing hero transformed on a scale unknown (8)
5. Cause offence about bad air on back of envy resulting in isolation (10)
6. Farmer's friend in spirit I introduced to partners at table (3)
7. Place to sit not adjusted for support (3)
8. Tories reviewing act defining marriage (12)
9. Description of column is about right? Yeah, sure! (6)
10. Madly suggest giving up some ground at first to get reinforcement (6)
11. Shortly Inland Revenue to up cost for mincing ham (10)
12. Trick show takes in the French (7)
13. Engineers loan in small denominations for majesty (12)
14. One who returns late's not ever taken back by a conservation group (8)

Down

1. Unwelcome remarks according to children, me included (10)
2. Startling! Director is on track to return with Crosby (10)
3. Lays low in south following troubled times (6)
4. 10A arguably is able (6)
5. Horse’s backward motion is a wrong action (4)
6. Criticise island becoming separate (8)
7. All square after loosing lead in rugby competition (5)
8. LIttle kids somersault and bounce (4)
9. Hard scale in engine component's removed by combustion in theory (10)
10. Time travelling feature (4)
11. Member of parliament in drunken state changing sides graciously (8)
12. Laugh about punch on the tip of nose and time in hospital department (10)
13. Blade ground initially to get point (4)
14. Scientist involved with senior deckhand it's rumoured (5)
15. Enthusiatic artists' circle? (6)
16. Skirt around beginning of avalanche at head of trail in mountain (6)