Invariably, Sarah goes out in a group (7)
I believe the answer is:
several
'out in a group' is the definition.
Both the definition and answer are adjectives. Perhaps you can see an association between them that I can't see?
'invariably sarah' is the wordplay.
I cannot really see how this works, but
'invariably' could be 'ever' (I've seen this in another clue) and 'ever' is found within the answer.
'sarah' could be 'sal' (Sally is a common pet form of Sarah) and 'sal' is located in the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'goes' is the link.
Can you help me to learn more?
(Other definitions for several that I've seen before include "Indefinite number more than two or three, but not many" , "A good few" , "More than one or two" , "Various, sundry" , "Reveals (anag.)" .)