Taking things quickly, takes repast briefly (5)
I believe the answer is:
haste
'taking things quickly' is the definition.
I can't tell whether this definition defines the answer.
'takes repast briefly' is the wordplay.
'takes' becomes 'has' ('have' can be a synonym of 'take').
'repast' becomes 'tea' (tea is a kind of repast).
'briefly' means to remove the last letter.
'tea' with its final letter taken away is 'te'.
'has'+'te'='HASTE'
Can you help me to learn more?
(Other definitions for haste that I've seen before include "Hurry, urgency" , "Heats (anag.)" , "Expedition" , "Urgency of action" , "Excessive speed or urgency" .)