People very rash to appear in numbers (6)
I believe the answer is:
nomads
'people' is the definition.
The answer is an example.
'rash to appear in numbers' is the wordplay.
'rash' becomes 'mad' (I can't justify this - if you can you should give a lot more credence to this answer).
'to appear in' indicates putting letters inside.
'numbers' becomes 'nos' ('no' is an abbreviation for number).
'mad' inserted inside 'nos' is 'NOMADS'.
'very' is the link.
Can you help me to learn more?
(Other definitions for nomads that I've seen before include "Travellers" , "Wandering people, roaming tribes" , "They travel from place to place seeking food and pasture" , "Homeless types" , "Damson for wandering tribes" .)