Sure to be available in a concertina arrangement (7)
I believe the answer is:
certain
'sure' is the definition.
(synonyms)
'available in a concertina arrangement' is the wordplay.
I cannot really understand how this works, but
'in' is present in the answer.
'a' is present in the answer.
The remaining letters 'cert' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
'to be' acts as a link.
Can you help me to learn more?
(Other definitions for certain that I've seen before include "bound" , "Absolutely sure" , "Nice art (anag)" , "Unquestionable" , "Particular" .)