Catholic leaving continent with undue speed (5)
I believe the answer is:
haste
'undue speed' is the definition.
(I've seen this before)
'catholic leaving continent' is the wordplay.
'catholic' becomes 'C' (abbreviation as in RC for Roman Catholic).
'leaving' suggests deleting specific letters.
'continent' becomes 'chaste' (similar in meaning).
'chaste' with 'c' taken away is 'HASTE'.
'with' acts as a link.
(Other definitions for haste that I've seen before include "impetuosity" , "make speed" , "Excessive speed or urgency" , "Urgency of action" , "More of this proverbially slows you down" .)