Check out crack (around two feet) that's unusual (9)
I believe the answer is:
different
'unusual' is the definition.
(similar in meaning)
'check out crack around two feet' is the wordplay.
I cannot quite see how this works, but
'feet' could be 'ff' (an abbreviation for foot written twice) and 'ff' is found in the answer.
'check out' could be 'die' ('check out' can informally mean to die) and 'die' is found within the leftover letters.
The remaining letters 'rent' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'that's' is the link.
Can you help me to learn more?
(Other definitions for different that I've seen before include "Dissimilar, unlike" , "Otherwise" , "Unusual" , "Distinct, separate" .)