Group therapy

[jaywhybee]

I know I will kick myself but despite previous clues:
21. Wine producer is annoyed about resistance to the first Merlot. Troublesome! (6) (the only 4-letter wine producer I can think of is 'vine' with r+m. Is this right?)
42. Music for church service (3,5) (no idea)
67. The entire number of horses grouped for daily exercise... (3,3) (is this job lot?)
80. Those Dagenham girls are in a poor state! (7) (is this a collective name for pipers?)

[Jammydodgem]

80 is indeed a collective term for pipers.
67 is not job lot. second word is correct, just look that up and the rest should become clear.
42 is one of the armed services
21 the wine producer is a vine plus first letters of resistance and merlot

[jaywhybee]

Jammydodgem - Thanks for putting me out of my misery on 21 and 42, I've just kicked myself very hard! Will continue to work on the other two.