Tramp's wearing tight cap (5)
I believe the answer is:
limit
'cap' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for limit that I've seen before include "Extremity" , "Extreme point" , "Boundary or restriction" , "Bound, restriction" , "Restrict - boundary" .)