Guardian Crossword 210

[Unicorn5]

Have done some, but am stuck on last six!

5D - Chocolate bar rubbish when taking running exercises (8) - ?E???I?S It looks like AEROBICS (Aero is a chocolate bar), but I can't understand the "BICS" bit at the end.

11A - Types of plant cultivar finally introduced to part of East Anglia (5) B?N??, but I think that these letters are after enciphering.

15D - Perhaps the Rees-Moggs are away in the Trossachs on vacation (5) S?E?R, again I think that this is after enciphering.

21A - Hawk in small hole (4) - could this be SPIT before enciphering?

17D - Useless opponents, city men on holiday? (5) D???S

30A - Long walk back - note squashed frog (4) C?N? after enciphering. Feels like it should have something to do with Kermit the frog as this contains TREK backwards, but can't for the life of me work out how to parse!

Many thanks for any help.

[Toorak]

25 toffs - off (away) in t(rossach)s

[Toorak]

11 ferns - (cultiva)r inside fens

[Toorak]

30 - Kermit reversed minus mi (note) = trek

[JJ109]

21 Spit is correct
17d Dudes

[chelle7272]

bics ;
bs (bull *** - rubbish) around ic (in charge - running)

[JJ109]

Aero + BS(rubbish) around IC (in charge/running)

[JJ109]

21 - .....spit needs to be enciphered!

[Unicorn5]

Thank you very much everybody. Thought that Kermit has something to do with it, but I'd never have got the bull**** one!