Sort of heel giving a bit of trouble in prison! (5)
I believe the answer is:
cuban
'sort of heel' is the definition.
(I've seen this before)
'a bit of trouble in prison' is the wordplay.
'a bit of trouble' becomes 'ub' (I can't explain this - if you can you should give a lot more credence to this answer).
'in' is an insertion indicator.
'prison' becomes 'can' (the can is American slang for prison).
'ub' going into 'can' is 'CUBAN'.
'giving' acts as a link.
Can you help me to learn more?
(Other definitions for cuban that I've seen before include "Havana native" , "Like Fidel Castro" , "Expensive kind of cigar" , "One from Havana" , "Citizen of Castro's country" .)