I'm thinking it's ONCE IN A BLUE MOON but can't work out why.

I meant to add this:
Hesitate about small business centre (4)

[Chalky] CO (small business) + RE ("er" backwards).

[rab]Spot on; it's an anagram but with an M (my first) removed - it would have been harder (but still I think acceptable) to have not included the "- and only very rarely" - the definition then being the "Uncommon" which doubled up as part of the anagram.

Hmmm - Apologies - I've just looked at it and seen that somehow I missed out the B - sorry, sorry, sorry - will check them better in future.

Nothing still outstanding?
It's not right to scry the lawnmower. (6)
He'll summon you for taking a bad grip on a faulty reamer. (4,6)

Second one would be GRIM REAPER?
Sorry, it hit me straight away - I'll have a look at the first one when I'm finished what I'm up to.

Your first, Raak would be SCYTHE ?

*chuckles* I'm a bit slow - I only saw the connection 'tween the two after I'd posted my last entry.

... Is Raak hinting something ... ?

The time has come for this one or Huw ! (3,2,3,4)
Running up to a mate ? (3-4)
Get memory back ? Now begin, cringe not badly - The aroma of a great game !(10,8)

(Boldly)

I think I've got the third of those... but I suspect we really need to solve the first two first!

I perhaps ought to modify the first one slightly ...
The time has come for this one or Huw - that's crazy ! (3,2,3,4)
Running up to a mate ? (3-4)
Get memory back ? Now begin, cringe not badly - The aroma of a great game !(10,8)

[rab,Blob] They are NOW IS THE HOUR and END GAME. I wonder what the third could be?

It looks like it might be Mornington Crescent.

Whoops, didn't mean to be so bold...